8GESTATIONAL AGE Fertilization LMP Days 266 280 Weeks 38 40 Gestational age=Time since last menstrual period (LMP)EDC, EDD, EDB266 Days after fertilization280 Days after onset of LMPFertilization LMPDaysWeeksCalendar Months 8 3/4 9Lunar Months 9 1/2 10
9GESTATIONAL AGE Nagele’s Rule Add 7 days to the first day of the last normal menstrual period, subtract 3 months and add 1 year.Example:1st day of LNMP=Decemberadd 7 days = Decsubtract 3 months = Septadd 1 year =Sept , estimated due date (EDD)
12FETAL MEMBRANES Amnion Chorion Membranes: Decidua basalis Decidua capsularisDecidua basalisDeveloping placentaYolk sacAmniotic cavityIntrauterine cavityDecidua veraMucus plug (operculum)Chorion (blends with placenta)Amnion (blends with umbilical cord)Membranes:Umbilical cord (funis)Villi of fetal portion of placenta filled with fetal bloodLacunae in decidua basalis filled with maternal bloodAmnionChorion
131 Month First Trimester At the end of four weeks: Baby is 1/4 inch in lengthHeart, digestive system, backbone and spinal cord begin to formPlacenta (sometimes called "afterbirth") begins to developThe single fertilized egg is now 10,000 times larger than size at conception
14Month 2 First Trimester At the end of 8 weeks: Baby is 1-1/8 inches longHeart is functioningEyes, nose, lips, tongue, ears and teeth are formingPenis begins to appear in boysBaby is moving, although the mother can not yet feel movement
15Month 3 First Trimester At the end of 12 weeks: Baby is 2 1/2 to 3 inches longWeight is about 1/2 to 1 ounceBaby develops recognizable form. Nails start to develop and earlobes are formedArms, hands, fingers, legs, feet and toes are fully formedEyes are almost fully developedBaby has developed most of his/her organs and tissuesBaby's heart rate can be heard at 10 weeks with a special instrument called a Doppler
16Month 4 Second Trimester At the end of 4 months: Baby is 6 1/2 to 7 inches longWeight is about 6 to 7 ouncesBaby is developing reflexes, such as sucking and swallowing and may begin sucking his/her thumbTooth buds are developingSweat glands are forming on palms and solesFingers and toes are well definedSex is identifiableSkin is bright pink, transparent and covered with soft, downy hairAlthough recognizably human in appearance, the baby would not be able to survive outside the mother's body
17Month 5 Second Trimester At the end of 5 months: Baby is 8 to 10 inches longWeight is about 1 poundHair begins to grow on baby's headSoft woolly hair called lanugo will cover its body. Some may remain until a week after birth, when it is shed.Mother begins to feel fetal movementInternal organs are maturingEyebrows, eyelids and eyelashes appear
18Month 6 Second Trimester At the end of 6 months: Baby is 11 to 14 inches longWeight is about 1 3/4 to 2 poundsEyelids begin to part and eyes open sometimes for short periods of timeSkin is covered with protective coating called vernixBaby is able to hiccup
19Month 7 Third Trimester At the end of 7 months: Baby is 14 to 16 inches longWeight is about 2 1/2 to 3 1/2 poundsTaste buds have developedFat layers are formingOrgans are maturingSkin is still wrinkled and redIf born at this time, baby will be considered a premature baby and require special care
20Month 8 Third Trimester At the end of 8 months: Baby is 16 1/2 to 18 inches longWeight is about 4 to 6 poundsOverall growth is rapid this monthTremendous brain growth occurs at this timeMost body organs are now developed with the exception of the lungsMovements or "kicks" are strong enough to be visible from the outsideKidneys are matureSkin is less wrinkledFingernails now extend beyond fingertips
21Month 9 Third Trimester At the end of 9 months: Baby is 19 to 20 inches longWeight is about 7 to 7 1/2 poundsThe lungs are matureBaby is now fully developed and can survive outside the mother's bodySkin is pink and smoothBaby settles down lower in the abdomen in preparation for birth and may seem less active
22AMNIOTIC FLUIDClear, yellowish fluid surrounding the developing fetus.Average amount 1000 ml.Having < 300ml – Oligohydramnios, associated with fetal renal abnormalities.Having > 2 L – Hydramnios, associated with GI and other malformations.
23AMNIOTIC FLUID Protects Fetus Controls Temperature Supports Symmetrical GrowthPrevents Adherence to amnionAllows MovementSource of oral fluidActs as a excretion-collection repository
24UMBILICAL CORD Connecting link between fetus and placenta. Transports oxygen and nutrients to fetus from the placenta and returns waste products from the fetus to the placenta.Contains: 2 arteries and 1 vein supported by mucoid material (wharton’s jelly) to prevent kinking and knotting.Contains NO pain receptors.
26PLACENTA MOM Baby Baby mom Schematic drawing of placenta: how it supplies oxygen and nutrition to embryo and removes waste products. Deoxygenated blood leaves fetus through the umbilical arteries and enters placenta, where it is oxygenated. Oxygenated blood leaves placenta through the umbilical vein, which enters the fetus via the umbilical cordmomMOMBabyBaby
27PLACENTA Produce protein hormones: Human chorionic gonadotrophin (HCG) days past conception, is basis for pregnancy testProgesteroneEstrogenHuman Placental Lactogen
28PLACENTASieve/filter – allows smaller particles through and holds back larger molecules. Passage of materials in either direction is effected by:Diffusion: gases, water, electrolytesFacilitated transfer: glucose, amino acids, minerals.Pinocytosis: movement of minute particle
29PLACENTAMother transmits immunoglobulin G (IgG) to fetus providing limited passive immunity.Leakage: caused by membrane defect: may allow maternal and fetal blood mixing.
30VIABILITYCapability of fetus to survive outside uterus at the earliest gestational age weeksSurvival depends on:Maturity of fetal central nervous systemMaturity of lungs
31RESPIRATORY SYSTEM 30-32 Weeks 1.2 : 1 35 Weeks 2:1 (MATURITY) Terminal SAC period Weeks to birthGrowth of primitive alveoliPulmonary surfactants produced which act as wetting agents that prevent alveolar walls from stickingInsufficient surfactant - RDSLecithin/Sphingomyelin-Phospho LipidsL/S Ratio30-32 Weeks 1.2 : 135 Weeks 2:1 (MATURITY)
32CARDIOVASCULAR SYSTEM 1st System to functionFHR /MinCan hear FHR with doppler at Weeks
33FETAL CIRCULATIONArteries in umbilical cord and fetal body carry deoxygenated blood.Vein in cord and those in fetal body carry oxygenated bloodDuctus venosus connects umbilical vein and inferior vena cava; bypassing portal circulation.
34FETAL CIRCULATIONForamen Ovale allows blood to flow from right to left atrium, bypassing lungs.Ductus Arteriosus allows blood flow from pulmonary artery to aorta, bypassing fetal lungs;
35HEPATIC SYSTEMLiver functions 4-6 weeksFull liver function after deliveryMUSCULO-SKELETAL SYSTEMBones and muscles develop by 4th weekFontanels – areas where >2 bones meet7-8 Weeks arms & leg movements
36GASTROINTESTINAL SYSTEM Forms during 4th weekMiddle portion of the intestine projects out into cord during 5th week. Returns during 10th week. If this does not occur- Omphalocele present at birthMeconium – Dark green to black tarry waste accumulated in the fetal intestine near term
37RENAL SYSTEMKidneys form in 5th week and begin to function 4 weeks later.Voiding into amniotic fluidLow volume can show renal dysfunctionRenal malformation can be diagnosed in utero.GFR is low at birth
38NEUROLOGICAL SYSTEM Formed from the ectoderm during the 3rd week Respiratory effort 18 1/2 WKSSwallowing /2 WKSSucking WKSFetal movement felt WKS(Quickening)
39ENDOCRINE SYSTEM INTEGUMENTARY SYSTEM Thyroid gland 1st to develop Insulin produced at 20 weeksINTEGUMENTARY SYSTEM7th week – Two layers of cellsVernix caseosa –Protects skinLanugo – Fine hair10th week – Fingernails, toenails
40IMMUNE SYSTEMPassive immunity - FROM MOMActive immunity - FROM FETUS