pregnancy: genetics, conception, fetal development

Pregnancy: genetics, Pregnancy: genetics, conception, fetal conception, fetal

developmentdevelopment

ConceptionConception

union of single egg and sperm, marks the beginning of the pregnancy

not at as isolated event but as a part of sequential process:

– gamete formation (egg and sperm)– ovulation (release of the egg)– fertilization (union of the gametes)– implantation in the uterus

Cell Division. MitosisCell Division. Mitosis the body cells replicate to yield two cells

with the same genetic makeup as the parent cell.

First the cell makes a copy of its DNA; then it divides, and each daughter cell receives one copy of the genetic material.

The purpose of mitotic division is for growth and development or cell replacement.

Cell Division. MeiosisCell Division. MeiosisThe process by which germ cells divide and

decrease their chromosomal number by half and produces gametes:– sperm in males– eggs in females

Human body cells contain 46 chromosomes (diploid)

Gametes contain 23 chromosomes (haploid)

Cell Division. Mitosis vs Cell Division. Mitosis vs MeiosisMeiosis

Gametogenesis: SpermatogenesisGametogenesis: SpermatogenesisBegins at puberty (400 million/day)Mitotic division of 1 diploid

spermatogonium (primitive sperm cell):– produces 2 daughter cells Primary

spermatocyte– contains diploid number of chromosomes– The cell has already copied its DNA before

devision, so four alleles for each gene are present. The cell is still considered diploid because the copies are bound together (one allele plus its copy on each chromosomes)

I mitotic division– Secondary spermatocytes

– contains 23 chromosomes one contains the X chromosome (plus its copy) and the other the Y chromosome (plus its copy).

Gametogenesis: SpermatogenesisGametogenesis: SpermatogenesisII mitotic division

–Spermatids (haploid)

–two gametes with an X chromosome

– two gametes with a Y chromosomeall of which will

–develop into viable spermEach primary spermatocyte:

– produces 4 spermatozoa

GametogenesisGametogenesis

Spermatogenesis primary spermatocytes (46)

2 haploid secondary spermatocyte(22X+22Y)

4 Spermatids

Gametogenesis:Gametogenesis: Oogenesis Oogenesis Begins during fetal life in the

female All cells contained in the ovaries

at birth The majority of the estimated 2

million primary oocytes (the cells that undergo the first meiotic division) degenerate spontaneously.

Only 400 to 500 ova will mature during the approximately 35 years of a woman's reproductive life.

Gametogenesis:Gametogenesis: Oogenesis Oogenesis Oogonia (stem cells of females)

complete mitotic divisions between third and seventh months gestation:– primary oocytes replicate their DNA but

remain suspended at this stage until puberty Maturation of primary oocyte and

completes the I Meiosis Division– producing 1 secondary oocyte (with

original cytoplasm)– and 1 polar body (that disintegrates)– 22 autosomes and 1 X sex chromosome

II Meiosis Division (at ovulation)– Ovum an & 3rd polar body are formed– The first polar also divides to form 2

additional polar bodies Result: 1 ovum+3 polar body

GametogenesisGametogenesis

Oogenesis Primary oocyte Secondary oocyte+polar body mature ovum+3 polar body

Gametogenesis: Spermatogenesis vs Gametogenesis: Spermatogenesis vs OogenesisOogenesis

OvumOvum

Meiosis occurs in the female in the ovarian follicles and produces an egg, or ovum. Each month, one ovum matures with a host of surrounding supportive cells.

At ovulation the ovum is released from the ruptured ovarian follicle. High estrogen levels increase the motility of the uterine tubes so their cilia are able to capture the ovum and propel it through the tube toward the uterine cavity. An ovum cannot move by itself.

OvumOvum Two protective layers surround the ovum. The inner layer is a thick, acellular layer, the zona

pelluada. The outer layer, the corona radiata, is composed of

elongated cells. Ova are considered fertile for approximately 24 hours

after ovulation. If unfertilized by a sperm, the ovum degenerates and is reabsorbed.

SpermSperm Ejaculation during sexual intercourse normally propels

almost a teaspoon of semen containing as many as 200 million to 500 million sperm into the vagina.

The sperm swim with the flagellar movement of their tails.

Some sperm can reach the site of fertilization within 5 minutes, but average transit time is 4 to 6 hours.

Sperm remain viable within the woman's reproductive system for an average of 2 to 3 days. Most sperm are lost in the vagina, within the cervical mucus, or in the endometrium, or they enter the tube that contains no ovum.

As sperm travel through the female reproductive tract, enzymes are produced to aid in their capacitation.

Capacitation is a physiologic change that removes the protective coating from the heads of the sperm. Small perforations then form in the acrosome (a cap on the sperm) and allow enzymes (e.g., hyaluronidase) to escape. These enzymes are necessary for the sperm to penetrate the protective layers of the ovum before fertilization.

FertilizationFertilization Takes place in the ampulla of uterine tube When a sperm successfully penetrates the membrane

surrounding the ovum, both sperm and ovum are enclosed within the membrane, and the membrane becomes impenetrable to other sperm; this is termed the zona reaction.

The second meiotic division of the oocyte is then completed, and the ovum nucleus becomes the female pronucleus. The head of the sperm enlarges to become the male pronucleus, and the tail degenerates.

The nuclei fuse and the chromosomes combine, restoring the diploid number (46).

Conception, the formation of the zygote, is now complete.

FertilizationFertilization


Mitotic cellular replication, called cleavage, begins as the zygote travels the length of the uterine tube into the uterus. This voyage takes 3 to 4 days.

Because the fertilized egg divides rapidly with no increase in size, successively smaller cells, blastomeres, are formed with each division.

A 16-cell morula, a solid ball of cells, is produced within 3 days, and is still surrounded by the protective zona pellucida. Further development occurs as the morula floats freely within the uterus.

Fluid passes through the zona pellucida into the intercellular spaces between the blastomeres, separating them into two parts: the trophoblast (which gives rise to the placenta) and the embryoblast (which gives rise to the embryo). A cavity forms within the cell mass as the spaces come together, forming a structure termed the blastocyst cavity.

When the cavity becomes recognizable, the whole structure of the developing embryo is known as the blastocyst. The outer layer of cells surrounding the cavity is the trophoblast

ImplantationImplantation The zona pellucida degenerates, and

the trophoblast attaches itself to the uterine endometrium, usually in the anterior or posterior fundal region.

Between 6 and 10 days after conception, the trophoblast secretes enzymes that enable it to burrow into the endometrium until the entire blastocyst is covered. This is termed implantation.

Endometrial blood vessels erode, and some women experience implantation bleeding (slight spotting and bleeding during the time of the first missed menstrual period).

ImplantationImplantation Chorionic villi, or fingerlike projections,

develop out of the trophoblast and extend into the blood-filled spaces of the endometrium. These villi are vascular processes that obtain oxygen and nutrients from the maternal bloodstream and dispose of carbon dioxide and waste products into the maternal blood

After implantation, the endometrium is termed the decidua.

The portion directly under the blastocyst, where the chorionic villi tap the maternal blood vessels, is the decidua basalis.

The portion covering the blastocyst is the decidua capsularis,

and the portion lining the rest of the uterus is the decidua vera

EMBRIO AND FETUSEMBRIO AND FETUS

EMBRIO AND FETUSEMBRIO AND FETUS Pregnancy lasts approximately 10 lunar months (9 calendar

months, 40 weeks, or 280 days). Length of pregnancy is computed from the first day of the last menstrual period (LMP) until the day of birth. However, conception occurs approximately 2 weeks after the first day of the LMP. Thus the postconception age of the fetus is 2 weeks less, for a total of 266 days, or 38 weeks. Postconception age is used in the discussion of fetal development.

Intrauterine development is divided into three stages:– preembryonic (from conception until day14. This period

covers cellular replication, blastocyst formation, initial development of the embryonic membranes, and establishment of the primary germ layers)

– Embryo (2nd week after fertilization until the end of the 2nd month. Development of organs and systems)

– Fetus (the 3rd through the 9th months of development)

Early Developmental StagesEarly Developmental StagesPrimary Germ LayersPrimary Germ Layers

Ectoderm, Mesoderm and Endoderm

During gastrulation, three major cell lineages are being established. They are the Ectoderm (shown in the diagram as blue), Mesoderm (red) and Endoderm (yellow). Following gastrulation, various cell lineages are derrived from these three primary cell types. For example, the Ectoderm gives rise to the epidermis and its derrivatives such as nails, hair and teeth. On the other hand, the Ectoderm also gives rise to the Central Nervous System.

Development of the embrioDevelopment of the embrio

MembranesMembranes At the time of implantation, two fetal membranes that will

surround the developing embryo begin to form. The chorion develops from the trophoblast and contains the chorionic villi on its surface. The villi burrow into the decidua basalis and increase in size and complexity as the vascular processes develop into the placenta. The chorion becomes the covering of the fetal side of the placenta. It contains the major umbilical blood vessels that branch out over the surface of the placenta. As the embryo grows, the decidua capsularis stretches. The chorionic villi on this side atrophy and degenerate, leaving a smooth chorionic membrane.

The inner cell membrane, the amnion, develops from the interior cells of the blastocyst. The cavity that develops between this inner cell mass and the outer layer of cells (trophoblast) is the amniotic cavity. As it grows larger, the amnion forms on the side opposite to the developing blastocyst. The developing embryo draws the amnion around itself to form a fluid-filled sac. The amnion becomes the covering of the umbilical cord and covers the chorion on the fetal surface of the placenta. As the embryo grows larger, the amnion enlarges to accommodate the embryo/fetus and the surrounding amniotic fluid. The amnion eventually comes in contact with the chorion surrounding the fetus.

AMNIOTIC FLUIDAMNIOTIC FLUID At first the amniotic cavity derives its fluid by diffusion from the maternal blood. The amount of

fluid increases weekly, and 800 to 1200 ml of transparent liquid is normally present at term. The amniotic fluid volume changes constantly.

– the fetus swallows fluid– fluid flows into and out of the fetal lungs– the fetus urinates into the fluid, greatly increasing its volume

Volume– Oligohydramnios - less than 300 ml of amniotic fluid is associated with fetal renal abnormalities– Hydramnios - more than 2 L of amniotic fluid is associated with gastrointestinal and other malformations

Function– helps maintain a constant body temperature– a source of oral fluid and as a repository for waste– protect the fetus from trauma by blunting and dispersing outside forces– allows freedom of movement for musculoskeletal development– keeps the embryo from tangling with the membranes

Amniotic fluid contains albumin, urea, uric acid, creatinine, lecithin, sphingomyelin, bilirubin, fructose, fat, leukocytes, proteins, epithelial cells, enzymes, and lanugo hair.

Study of fetal cells in amniotic fluid through amniocentesis yields much information about the fetus.

Genetic studies (karyotyping) provide knowledge about the sex and the number and structure of chromosomes. Other studies, such as the lecithin/sphingomyelin ratio, determine the health or maturity of the fetus.

Yolk SacYolk Sac At the same time the amniotic cavity and amnion are forming,

another blastocyst cavity forms on the other side of the developing embryonic disk. This cavity becomes surrounded by a membrane, forming the yolk sac. The yolk sac aids in transferring maternal nutrients and oxygen, which have diffused through the chorion, to the embryo. Blood vessels form to aid transport. Blood cells and plasma are manufactured in the yolk sac during the second and third weeks. At the end of the third week, the primitive heart begins to beat and circulate the blood through the embryo, connecting stalk, chorion, and yolk sac.

The folding in of the embryo during the fourth week results in incorporation of part of the yolk sac into the embryo's body as the primitive digestive system. Primordial germ cells arise in the yolk sac and move into the embryo.

The shrinking remains of the yolk sac degenerate. By the fifth or sixth week, the remnant has separated from the embryo.

Umbilical cordUmbilical cord By day 14 after conception the embryonic disk, amniotic sac, and

yolk sac are attached to the chorionic villi by the connecting stalk. During the third week the blood vessels develop to supply the embryo with maternal nutrients and oxygen. During the fifth week, after the embryo has curved inward on itself from both ends (bringing the connecting stalk to the ventral side of the embryo), the connecting stalk becomes compressed from both sides by the amnion, forming the narrower umbilical cord. Two arteries carry blood to the chorionic villi from the embryo, and one vein returns blood to the embryo.

The cord rapidly increases in length. At term the cord is 2 cm in diameter and ranges from 30 to 90 cm in length (with an average of 55 cm). It twists spirally on itself and loops around the embryo/fetus. A true knot is rare, but false knots occur as folds or kinks in the cord and may jeopardize circulation to the fetus. Connective tissue called Wharton's jelly prevents compression of the blood vessels and ensures continued nourishment of the embryo/fetus. Compression can occur if the cord lies between the fetal head and the pelvis or if it is twisted around the fetal body. When the cord is wrapped around the fetal neck, it is termed a nuchal cord.

Because the placenta develops from the chorionic villi, the umbilical cord is usually located centrally. A peripheral location is less common and is termed battledore placenta.

The blood vessels are arrayed out from the center to all parts of the placenta.

Placenta. Placenta. StructureStructure The placenta begins to form at implantation. During

the third week after conception, the trophoblast cells of the chorionic villi continue to invade the decidua basalis. As the uterine capillaries are tapped, the endometrial spiral arteries fill with maternal blood. The chorionic villi grow into the spaces with two layers of cells: the outer syncytium and the inner cytotrophoblast. A third layer develops into anchoring septa, dividing the projecting decidua into separate areas called cotyledons. In each of the 15 to 20 cotyledons, the chorionic villi branch out, and a complex system of fetal blood vessels forms. Each cotyledon is a functional unit. The whole structure is the placenta.

The maternal-placental-embryonic circulation is in place by day 17, when the embryonic heart starts beating.

By the end of the third week, embryonic blood is circulating between the embryo and the chorionic villi.

In the intervillous spaces, maternal blood supplies oxygen and nutrients to the embryonic capillaries in the villi. Waste products and carbon dioxide diffuse into the maternal blood.

Functions of the placenta:Functions of the placenta:

1. Transfer gasses2. Transport nutrients3. Excretion of wastes4. Hormone production – temporary endocrine

organ – estrogen and progesterone5. Formation of a barrier – incomplete,

nonselective – alcohol, steroids, narcotics, anesthetics, some antibiotics and some organisms can cross

Hormones of PlacentaHormones of Placenta human chorionic gonadotropin (hCG) – detected 8-10 days after conception or

shortly after implantation, basis of pregnancy test, preserves the function of the ovarian corpus luteum, ensuring a continued supply of estrogen and progesterone needed to maintain the pregnancy. Miscarriage occurs if the corpus luteum stops functioning before the placenta is producing sufficient estrogen and progesterone. The hCG reaches its maximum level at 50 to 70 days, then begins to decrease

human placental lactogen (hPL) or human chorionic somatomammotropin - similar to a growth hormone and stimulates maternal metabolism to supply needed nutrients for fetal growth. This hormone increases the resistance to insulin, facilitates glucose transport across the placental membrane, and stimulates breast development to prepare for lactation.

placental prolactin - Helps convert mammary glands to active status Relaxin- Increases flexibility of pubic symphysis, permitting pelvis to expand

during delivery Progesterone – maintains the endometrium, decreases the contractility of the uterus,

and stimulates development of breast alveoli and maternal metabolism Estrogens – stimulates uterine growth and uteroplacental blood flow, causes a

proliferation of the breast glandular tissue and stimulates myometrial contractility. Placental estrogen production increases greatly toward the end of pregnancy.

Extraembryonic Membranes & Placenta FormationExtraembryonic Membranes & Placenta Formation

Figure 29–5 (1 of 3)

G. Fetus at 2-3weeksG. Fetus at 2-3weeks

1/10 of an inch longnervous system is developingblood cells are developed

H. Fetus at 4 weeks

May float freely for 48 hours before implantingArm buds start to be evidentgets more of a curved appearanceeyes start to developimplantation of to the uterus and placenta is taking place

I. The Fetus at 5 weeksI. The Fetus at 5 weeks•The nose starts to form•Placental blood vessels form•endocardial(muscle) cells begins to form the two heart tubes

J. The Fetus at 6 weeks•1/2 inch long (floating in amniotic fluid)•leg buds present•spine is visible•ears are forming•at 6 weeks heart muscle starts to beat •has rapid growth at this stage•head/mouth/liver/intestines start to take shape

K. The Fetus at 7 weeksK. The Fetus at 7 weeks• 3/4 inches long

• Hand/fingers are formed and moving

•eye lens form

•skull bones are visible and growing

•sexual organs are forming

•brain waves have started

•muscles develop and get stronger

L. Fetus at 8-9 weeks oldL. Fetus at 8-9 weeks oldHeart Development Ends

The brain can move muscles

Sexual organs are forming

Feet become more defined

Digits are separating on hands/feet

Toe/Finger joints are visible

As you can see the fetus is in itsown sac of amniotic fluid attached tothe mother by an umbilical cordto the placenta where it gets all it’snourishment from. (Above are two twin boy fetuses in separate sacs)

M. 10 Week Old FetusM. 10 Week Old Fetus

(2 1/2 months old) Now considered a fetus• 1-2 inches long•Has a stump for a tail’• Is now very active• Facial features developed• Fingers/ Toes/ Hands/ Feet developed•Internal Organs are functioning• Nervous System is responsive: He/She can feel!

N. 11 Weeks old:

Now is 2 1/2 inches long

12 WEEKS(3 months)12 WEEKS(3 months)

•3 inches long•umbilical cord intact andis fully functional

14 WEEKS (3 1/2 months)14 WEEKS (3 1/2 months)

•3- 31/2 inches•weight is 1 ounce•muscles are developing•sex organs form•eyelids form•fingernails and toenails•spontaneous movement is observed

15-18 WEEKS15-18 WEEKS( 4-4 1/2 months)( 4-4 1/2 months)

•Sensory Organs form at (15)•(16) is turning inside of MOM•(18) 5 1/2 inches•blinks, grasps, moves mouth, hair on head and body is present •all systems are developed•fetal respiration's are occurring•Must be at least 24 weeks to survive outside of womb

WEEK 22 (2 1/2 months)WEEK 22 (2 1/2 months)•1/2 pound•10 inches long•sweat glands•external skin is turning from transparent to opaque

WEEK 26 WEEK 26 (6 1/2 Months(6 1/2 Months

•Inhales and exhales•cries•eyes are completely formed•has tongue and taste buds•has a 50% chance of survival outside of the womb with intensive Medical care

WEEK 30WEEK 30(7 1/2 months)(7 1/2 months) (7 1/2 mo.)

•Is premature if born•But most do well if born at this time•Girls fair better than boys because their lungs are more developed.

FULL TERM (36 -40 weeks)FULL TERM (36 -40 weeks)

This is the end of normalgestation….Baby is now able to live outside of the mother’s womb.

Normal pregnancyNormal pregnancy

The Start of It AllThe Start of It All

In either case, the process will In either case, the process will inevitably involve a sperm and an egginevitably involve a sperm and an egg

Or….for those women who get tired of Or….for those women who get tired of waiting for the “right man”waiting for the “right man”

Pregnancy is a normal Pregnancy is a normal physiologic process . . . physiologic process . . .

. . . not a disease!

Signs of pregnancySigns of pregnancy

Presumptive (generally subjective) Probable (objective) Positive (diagnostic)

Presumptive symptoms Presumptive symptoms of pregnancy:of pregnancy:Cessation of mensesNausea with or without vomitingFrequent urinationFatigueBreast tenderness, fullness, tinglingMaternal perception of fetal movement

(“Quickening”)

Presumptive signs of Presumptive signs of pregnancy:pregnancy:Breast changes – enlargement,

hyperpigmentation, Montgomery’s tuberclesBluish or purplish coloration of the vaginal

mucosa and cervix (Chadwick’s sign) Increased skin pigmentation – chloasma,

linea nigraAppearance of striae on abdomen and

breasts

Probable signs of Probable signs of pregnancy:pregnancy:Enlargement of the abdomenChanges in the size, shape, and

consistency of the uterusChanges in the cervixPalpation of Braxton-Hicks contractionsOutlining the fetus manuallyEndocrine tests of pregnancy

Positive signs of Positive signs of pregnancy:pregnancy:Identification of the fetal heart beat

separately and distinctly from that of the mother

Perception of fetal movements by the examiner

Visualization of pregnancy on ultrasoundFetal recognition on X-ray

Expected Physical Changes - Expected Physical Changes - CardiovascularCardiovascular

Blood volume increase Physiological anemia Vital signs stable Increased clotting factors Edema

Cardiovascular Changes During PregnancyCardiovascular Changes During Pregnancy Heart Rate: 15% ( 10-20 bpm) Stroke Volume: 50% Cardiac Output: 30-50% (6.2±1.0 L/min)

– Nonpregnant is 4.30.9 L/min Blood Pressure: 3-5 mmHg systolic and 5-10

mmHg diastolic in the first trimester and returns to the patient’s prepregnant level

by term Systemic Vascular Resistance: 21% (1210

dyne·cm·sec-5 versus 1530 dyne·cm·sec-5 ) Colloid Oncotic Pressure: 20% (18.0 ±1.5

mmHg)– Nonpregnant is 20.8 ±1.0 mmHg

Hematologic Changes During PregnancyHematologic Changes During Pregnancy Blood Volume: 45% ( 1450-1750 ml)

– Protects the mother from devastating hemorrhage at delivery

Plasma Volume: 45-50% ( 1200-1300 ml)– Serves to dissipate fetal heat production

Red Cell Mass: 18-30% ( 250-450 ml)– Necessary to O2 transport to meet fetal needs

Based on the above, pregnancy normally results in a “physiologic anemia”– Hgb: 10-12 g/dL (nonpregnant = 12-15 g/dL)

– Hct: 32-40% (nonpregnant = 35-47%)

Hematologic Changes During Pregnancy—Hematologic Changes During Pregnancy—cont.cont.

WBC: – 1st Trimester: 3,000-15,000/mm3

(mean 9500/ mm3)– 2nd & 3rd Trimesters: 6,000-16,000/mm3

(mean 10,500/ mm3)– Labor: 20,000-30,000/mm3

Expected Physical Changes- Expected Physical Changes- RespiratoryRespiratory

Oxygen consumption increases with decrease airway resistance

Deeper respirations and upward pressure on diaphragm

Respiratory Changes During PregnancyRespiratory Changes During Pregnancy Respiratory Rate: Unchanged or slight Tidal Volume (Vt): 30-40%

– This occurs at the expense of the expiratory reserve volume (ERV) which 20%

– Vital capacity (VC) & inspiratory reserve volume (IRV) remain relatively stable

Respiratory Changes During PregnancyRespiratory Changes During Pregnancy pH: slight to 7.40-7.45

– Remains roughly at nonpregnant level because the PaCO2 is compensated for by renal excretion of bicarbonate (HCO3)

Serum HCO3: (18-31 mEq/L) Oxygen consumption: 15-29% PaO2: 104-108 mmHg PaCO2: 27-32 mmHg

– ~40 mmHg in nonpregnant women– The above change in PaO2 and PaCO2 is very

important b/c it the CO2 gradient between the fetus and mother, therefore, facilitating the transfer of CO2 from the fetus to the mother

Expected Physical Changes - Expected Physical Changes - Gastrointestinal and Urinary Gastrointestinal and Urinary SystemsSystems

Nausea, vomiting, constipation, slowed peristalsis Bladder capacity increases and tone decreases; risk

of UTIs increases

GI ChangesGI Changes

AppetiteGastric emptyingAbsorptionBowel soundsBlood flow to the pelvisMorning sicknessPyrosisConstipation

Gallbladder and LiverGallbladder and Liver

Gallbladder with decreased tone

Renal Function Changes During PregnancyRenal Function Changes During Pregnancy Kidneys enlarge with a length of ~1 cm as

measured by intravenous pyelography Renal Plasma Blood Flow

30-50% by the end of the first trimester GFR

30-50% by the end of the first trimester The in Renal Plasma Flow and GFR are

responsible for decreases in the following:– Uric acid (serum) 4.5 mg/dL– BUN (serum) 12 mg/dL– Creatinine (serum) 0.5-0.6 mg/dL

Creatinine Clearance 150-200 mL/min

Clotting Factor Changes During PregnancyClotting Factor Changes During PregnancyFibrin: 40% at termPlasma Fibrinogen (Factor I): 50%Clotting time: UnchangedCoagulation Factors V, VII, VIII, IX, X,

XII all Coagulation Factors XI, XIII both slightlyProthrombin time: Unchanged or slightlyPlatelets: Unchanged

Expected physical changes -Expected physical changes -Integumentary SystemIntegumentary System

Hyperpigmentation Linea Nigra Melasma

Skin ChangesSkin Changes

Increased subdermal fat Hyperpigmentation Striae Linea nigra Chloasma Angiomas Pruritis Palmar erythema Increased perspiration

Endocrine ChangesEndocrine Changes

AmenorrheaProgesteroneEstrogenAnt pituitary suppresses the FSH and LH

causing to risePost pituitary produces oxytocin

Neurological ChangesNeurological Changes

Carpal Tunnel SyndromeNumbness/TinglingLightheadednessMuscle Cramps

Musculoskeletal ChangesMusculoskeletal Changes

Change in postureWaddlingBack Pain

Assessment of Assessment of Gestational AgeGestational AgeBy LMP (last menstrual period) – the

mean length of a normal pregnancy is 280 days from the first day of the last normal menstrual period

By physical exam

By ultrasound

Using the “Wheel”Using the “Wheel” Put the arrow marked FIRST DAY OF LMP on the appropriate date

The arrow marked APPROXIMATE DATE OF DELIVERY at the 40-week mark gives you the EDD

Today’s date gives you the EGA today

Nagele’s RuleNagele’s Rule

Subtract 3 months from that date then add 7 days

1st day of LNMP (last normal menstrual period)

Example: LNMP: September 10, 2006

Expected Due Date (EDD): June 17, 2007

Uterine SizingUterine Sizing6 weeks – globular with softening of the isthmus, size of a tangerine

8 weeks – globular, size of a baseball

10 weeks – globular with irregularity around one cornua (Piskacek’s sign), size of a softball

12 weeks – globular, size of a grapefruit

Uterine enlargement 12 weeks – At Symphysis 16 weeks – Midway between symphysis and

umbilicus 20 weeks – At the umbilicus 36 weeks - Near xyphoid process

Expected Physical Changes - Expected Physical Changes - Reproductive SystemReproductive System

Uterine SizingUterine Sizing

Accuracy of Dating by Accuracy of Dating by UltrasoundUltrasound

Gestational Age weeks)

Ultrasound Measurements

Range of Accuracy

< 8 Sac size + 10 days

8-12 CRL + 7 days

12-15 CRL, BPD + 14 days

15-20 BPD, HC, FL, AC + 10 days

20-28 BPD, HC, FL, AC + 2 weeks

> 28 BPD, HC, FL, AC + 3 weeks

The TrimestersThe TrimestersThe “trimesters” are three periods of 14

weeks each

1st trimester = through completion of 14 weeks

2nd trimester = through completion of 28 weeks

3rd trimester = 29th through 42nd weeks

Gravida and ParaGravida and ParaGravida means a woman who has been, or

currently is, pregnant

Para means a woman who has given birth

Nulligravida – never been pregnant Primigravida – pregnant for the first time Primipara – has delivered once Multipara – has delivered more than once

G T P A LG T P A LG – GRAVIDA (how many pregnancies)T – TERM (how many term deliveries)P – PRETERM (how many preterm

deliveries)A – ABORTIONS (how many abortions,

spontaneous or induced)L – LIVING – how many children

currently living

Term, Preterm, AbortionTerm, Preterm, AbortionTERM means delivery occurring in weeks

38-42PRETERM means delivery occurring in

weeks 20-37ABORTION means delivery occurring

before 20 weeksPOSTTERM means delivery occurring

after week 42

Psychological Adaptation Psychological Adaptation and Developmental Tasks and Developmental Tasks of Pregnancyof Pregnancy1st Trimester

– Accepting reality of pregnancy

2nd Trimester– Resolving feelings about her own mother; defining

herself as a mother

3rd Trimester– Active preparation for childbirth and baby

Review of Systems – 1Review of Systems – 1stst TrimesterTrimester Nausea Vomiting Headaches Dizziness Cramping Urinary frequency

Pain with urination Changes in discharge

(amount, color, odor) Pruritis Bleeding

Review of System – 2Review of System – 2ndnd TrimesterTrimester Gums bleeding Nose bleeding Constipation Fetal movement

Cramping Bleeding Dysuria Abnormal discharge pruritis

Review of Systems – 3rd Review of Systems – 3rd TrimesterTrimester Indigestion Swelling Leg cramps Fetal movement Difficulty sleeping

Contractions Bleeding Calf pain Headaches Epigastric pain Visual changes

History - MenstrualHistory - MenstrualMenarcheIntervalLengthRecent birth

control or lactation

LMP

– Sure of date?

– Normal in length & flow

Other helpful tidbits

– Date of conception

– ER sonogram

Obstetric HistoryObstetric History

Dates of all pregnancies (include previous miscarriage or termination)

GAGender, weightLength of laborCoping techniquesRoute of delivery

Gynecologic HistoryGynecologic History

Last PapAbnormal papGyn surgery or problems (e.g. infertility)Family planning methodsSexually transmitted infections

Medical/Surgical HistoryMedical/Surgical History

Serious illnessesHospitalizationsSurgeryDrug allergies or unusual reactionsMeds since LMP

Family HistoryFamily History

Maternal– Diabetes– Pre-eclampsia– Preterm delivery– Cancers (breast,

ovarian, colon)– Depression, bipolarity– Twins– Anesthesia reactions

Maternal or Paternal– Birth defects

– Mental retardation

– Bleeding disorders

– Chromosomal abnormalities (e.g. Down Syndrome)

Vital SignsVital Signs Temperature Blood pressure Respirations Radial pulse

Elevated BP suggests the presence of pre-eclampsia.

Elevated BP may be defined as a persistently greater than 140 systolic or 90 diastolic. Usually, if one is elevated, both are elevated.

Elevated temperature suggests the possible presence of infection.

Many pregnant women normally have oral temperatures of as much as 99+. These mild elevations can also be an early sign of infection.

While a pregnant pulse of up to 100 BPM or greater may be normal, rapid pulse may also indicate hypovolemia.

Additional MeasurementsAdditional Measurements

HeightWeightBMI (Body mass index )

– BMI Categories: – Underweight = <18.5 – Normal weight = 18.5-24.9 – Overweight = 25-29.9 – Obesity = BMI of 30 or greater

The First Prenatal Visit: The First Prenatal Visit: HistoryHistoryPast medical historyFamily medical historyGynecologic historyPast OB historyExposures to infections, teratogens,

genetic problemsSocial historyNutritional status

The First Prenatal Visit: The First Prenatal Visit: ExamExam Fundoscopic exam Teeth Thyroid Breasts Lungs Heart Abdomen Extremities

Skin Lymph nodes

The First Prenatal Visit: The First Prenatal Visit: Pelvic ExamPelvic Exam Vulva Vagina Cervix Uterine size Adnexae Rectum

Labs:– Pap– GC & chlamydia

Clinical pelvimetry:– Diagonal conjugate

– Ischial spines

– Sacrum

– Subpubic arch

– Gynecoid pelvic type?

Bones and Joints of the Bones and Joints of the PelvisPelvis

The Diagonal ConjugateThe Diagonal Conjugate The obstetric conjugate

extends from the middle of the sacral promontory to the posterior superior margin of the pubic symphysis. This is the most important diameter of the pelvic inlet.

The diagonal conjugate extends from the subpubic angle to the middle of the sacral promontory and can be measured clinically to estimate the obstetric conjugate.

The Ischial SpinesThe Ischial Spines The transverse

diameter, between the ischial spines, is a measurement of the dimensions of the pelvic cavity

The Pelvic OutletThe Pelvic Outlet Subpubic arch

Bituberous (transverse) diameter

Inferior pubic rami

The First Prenatal Visit: The First Prenatal Visit: LabsLabsABO blood type

D (Rh) typeAntibody screenCBCRubellaVDRL or RPRHBsAgHIV (optional)Hemoglobin electrophoresis (as appropriate)

The First Prenatal Visit: The First Prenatal Visit: CounselingCounseling What to expect

during the course of prenatal care

Risk factors encountered

Nutrition Exercise Work Sexual activity

Travel, seat belts Smoking cessation Avoidance of drugs

and alcohol Warning signs Where to go or call

in case of problems

Prenatal vitamins

The Return Prenatal VisitThe Return Prenatal Visit

REVIEW THE CHART!– Calculate the EGA– Check the labs– Review weight gain– Review blood pressure– Review results of UA

Leopold's ManeuversLeopold's Maneuvers - - are used to determine are used to determine the orientation of the fetus through abdominal the orientation of the fetus through abdominal

palpation.palpation. 1. Using two

hands and compressing the maternal abdomen, a sense of fetal direction is obtained (vertical or transverse).

.

2. The sides of the uterus are palpated to 2. The sides of the uterus are palpated to determine the position of the fetal back and small determine the position of the fetal back and small parts.parts.

3. The presenting part (head or butt) is palpated 3. The presenting part (head or butt) is palpated above the symphysis and degree of engagement above the symphysis and degree of engagement determineddetermined

4. The fetal occipital prominence is 4. The fetal occipital prominence is determined.determined.

Measuring Fundal HeightMeasuring Fundal Height

Auscultating Fetal Heart Auscultating Fetal Heart TonesTones

The Routine OB Visit The Routine OB Visit ScheduleScheduleEvery 4 weeks until 28 weeks

Every 2 weeks from 28 until 36 weeks

Every week from 36 weeks until delivery

Six weeks postpartum

Other Routine OB LabsOther Routine OB Labs 15-20 weeks

24-28 weeks

35-37 weeks

Quad Screen

Diabetes Screen Rhogam workup &

injection

Group B strep culture

Pregnancy is a normal Pregnancy is a normal physiologic process, not physiologic process, not a disease . . . a disease . . .

however, pregnancy tends to be UNCOMFORTABLE.

Your challenge is to differentiate common discomforts of pregnancy from pathology!

Nausea with or without Nausea with or without VomitingVomitingStarts at 4-6 weeks, peaks at 8-12 weeks,

resolves by 14-16 weeksCauses: unknown; may be rapidly

increasing and high levels of estrogen, hCG, thyroxine; may have a psychological component

Rule out: hyperemesis gravidarum

Nausea and vomiting in early Nausea and vomiting in early pregnancypregnancyIf a woman requests or would like to

consider treatment, the following interventions appear to be effective in reducing symptoms:

non-pharmacological

– ginger – P6 acupressure

pharmacological

– antihistamines. A

PtyalismPtyalism Excessive salivation

accompanied by nausea and inability to swallow saliva

Cause: unknown; may be related to increased acidity in the mouth

FatigueFatigue

Causes: unknown; may be related to gradual increase in BMR

Rule out: anemia, thyroid disease

BackacheBackacheWomen should be

informed that exercising in water, massage

therapy might help to ease backache during

pregnancy. A

Upper BackacheUpper Backache

Cause: increase in size and weight of the breasts

Relief: well-fitting, supportive bra

Low BackacheLow Backache

Cause: weight of the enlarging uterus causing exaggerated lumbar lordosis

Rule out: pyelonephritis (CVAT)

LeukorrheaLeukorrheaDefinition: a profuse, thin or thick white

vaginal discharge consisting of white blood cells, vaginal epithelial cells, and bacilli; acidic due to conversion of an increased amount of glycogen in vaginal epithelial cells into lactic acid by Doderlein’s bacilli

Rule out: vaginitis, STI, ruptured membranes

Urinary FrequencyUrinary Frequency 1st trimester: increased

weight, softening of the isthmus, anteflexion of the uterus

3rd trimester: pressure of the presenting part

Rule out: UTI

HeartburnHeartburn Relaxation of the cardiac

sphincter due to progesterone Decreased GI motility due to

smooth muscle relaxation (progesterone)

Lack of functional room for the stomach because of its displacement and compression by the enlarging uterus

Rule out: GI disease

HeartburnHeartburnWomen who present with

symptoms of heartburn in pregnancy should be offered information regarding lifestyle and diet modification.

Antacids may be offered to women whose heartburn remains troublesome

GPP

A

ConstipationConstipation Decreased peristalsis due to

relaxation of the smooth muscle of the large bowel under the influence of progesterone

Displacement of the bowel by the enlarging uterus

Administration of iron supplements

ConstipationConstipationWomen who present with constipation in pregnancy

should be offered information regarding diet modification, such as bran or wheat fibre

supplementation.A

HemorrhoidsHemorrhoids Relaxation of vein walls and

smooth muscle of large bowel under influence of progesterone

Enlarging uterus causes increased pressure, impeding circulation and causing congestion in pelvic veins

Constipation

HemorrhoidsHemorrhoidsWomen should be offered

information concerning diet modification.

If clinical symptoms remain troublesome, standard hemorrhoids creams should be considered.

GPP

Leg CrampsLeg Cramps Cause: unknown. ? inadequate calcium, ? Imbalance in

calcium-phosphorus ratio

Relief: straighten the leg and dorsiflex the foot:

Dependent EdemaDependent Edema Cause: impaired

venous circulation and increased venous pressure in the lower extremities

Rule out: preeclampsia

VaricositiesVaricosities Impaired venous circulation and increased

venous pressure in lower extremities Relaxation of vein walls and surrounding smooth

muscle under the influence of progesterone Increased blood volume Familial predisposition

Varicose veinsVaricose veinsVaricose veins are a common

symptom of pregnancy that will not cause harm and

Compression stockings can improve the symptoms but will not prevent varicose veins from emerging. A

Vaginal dischargeVaginal dischargeWomen should be informed that an increase in vaginal

discharge is a common physiological change that occurs during pregnancy.

GPP

If vaginal discharge is associated with itching, soreness, offensive smell or pain on passing urine there may be an infective cause

and investigation should be considered.

Vaginal dischargeVaginal discharge

GPP

A 1-week course of a topical imidazole is an effective treatment and should be considered for vaginal

candidiasis infections in pregnant women.


A

The effectiveness and safety of oral treatments for vaginal candidiasis in pregnancy is uncertain and these should not be

offered.


GPP

InsomniaInsomnia

Discomfort of the enlarged uterus Any of the common discomforts of pregnancy Fetal activity Psychological causes

Round Ligament PainRound Ligament Pain Round ligaments attach on either side of the uterus just below and in front of insertion of fallopian tubes, cross the broad ligament in a fold of peritoneum, pass through the inguinal canal, insert in the anterior portion of the labia majora

When stretched, they hurt!

Hyperventilation Hyperventilation and Shortness of Breathand Shortness of Breath Causes:

– Increase in the BMR– Pressure of the uterus on

the diaphragm– Changes in the oxygen-

carbon dioxide balance– Exertion of carrying extra

weight

Rule out: asthma, pneumonia, TB, anxiety

Supine Hypotensive Supine Hypotensive SyndromeSyndrome

Screening for hematological

conditions

AnemiaAnemiaPregnant women should be

offered screening for anaemia. Screening should take place early

in pregnancy (at the first appointment) and at 28 weeks.

This allows enough time for treatment if anaemia is detected.

B

Hemoglobin levels outside the normal range for pregnancy (that is, 11 g/dl at first contact

and 10.5 g/dl at 28 weeks) should be investigated and iron supplementation considered

if indicated.

AnemiaAnemia

A

Blood grouping and Blood grouping and red cell alloantibodies red cell alloantibodies

Women should be offered testing for blood group and RhD status in early

pregnancy.

BB

If a pregnant woman is RhD-negative, offer partner testing

to determine whether the administration of anti-D prophylaxis is necessary.

BB


It is recommended that routine antenatal anti-D

prophylaxis is offered to all non-sensitized pregnant

women who are RhD negative.


NICE 2002

Women should be screened for atypical red cell

alloantibodies in early pregnancy and again at 28

weeks regardless of their RhD status.

Blood grouping and Blood grouping and red cell red cell alloantibodiesalloantibodies

D

Pregnant women with clinically significant atypical red cell

alloantibodies should be offered referral to a specialist centre for further investigation and advice

on subsequent antenatal management.

Blood grouping and Blood grouping and red cell red cell alloantibodiesalloantibodies

GPP

pregnancy: genetics, conception, fetal development

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