human pregnancy

Human PregnancyHuman Pregnancy

How Long is the Human How Long is the Human Pregnancy?Pregnancy?

PregnancyPregnancyThe medical The medical

establishmentestablishmentDevelopmental Developmental

BiologistBiologistGeneral Public General Public

(US)(US)

Beginning PointBeginning PointDay 1 of last Day 1 of last

menstrual menstrual periodperiod

FertilizationFertilizationFirst missed First missed menstrual menstrual

periodperiod

Length of Length of PregnancyPregnancy

9.2 months9.2 monthsoror

40 weeks40 weeksoror

280 days280 days



266 days266 days



252 days252 days

FertilizationFertilization

Pre-embryo DevelopmentPre-embryo Development

Day 1 Fertilization

Day 3 Morula

Day 4 Early Blastocyst

Day 5 Late Blastocyst

Implantation Implantation Days 7- 10Days 7- 10

Ectopic pregnancyEctopic pregnancy

Success RatesSuccess Rates

30% of all fertilized eggs fail to implant30% of all fertilized eggs fail to implant70% implants70% implants– 20% miscarriage20% miscarriage– 1% stillborn1% stillborn– 79% live births (55% of all fertilized eggs)79% live births (55% of all fertilized eggs)

2% major congenital defects2% major congenital defects11% minor congenital differences11% minor congenital differences87% healthy babies87% healthy babies

..

Blastocytes produceBlastocytes produce

Proteases Proteases – Break down cells of the uterine endomitriumBreak down cells of the uterine endomitrium

Human Chorionic Hormone (HCG)Human Chorionic Hormone (HCG)– Maintain the Corpus Luteum (progesterone production)Maintain the Corpus Luteum (progesterone production)

Placenta formationPlacenta formation

HormonesHormones

PlacentaPlacentaThere is no exchange of blood between mother and There is no exchange of blood between mother and fetusfetusMost substances are filteredMost substances are filtered– There are some exceptionsThere are some exceptions

Some virus (HIVSome virus (HIVSome bacteria (Syphilis)Some bacteria (Syphilis)Alcohol, cocaine, other drugsAlcohol, cocaine, other drugs

– The effect of those substances will depend of the structure developing The effect of those substances will depend of the structure developing at the time and the dose.at the time and the dose.

The Placenta plays a role in preventing the mother’s The Placenta plays a role in preventing the mother’s immunological system from rejecting the embryo.immunological system from rejecting the embryo.

Some times cells are exchanged!Some times cells are exchanged!

Placenta separate mother / fetus Placenta separate mother / fetus bloodblood

MicrochimerismMicrochimerism

20% of adults have cells from their mothers

50% women (pregnancy past) have cells from the fetus decades after the pregnancy

Scientists have found a correlation between microchimerism and autoimmune disorders

First trimester First trimester Embryo developmentEmbryo development

7-8 weeks: can detect heartbeat, spinal 7-8 weeks: can detect heartbeat, spinal canal, arms/legs, fingers/toescanal, arms/legs, fingers/toes

now officially described as a fetus. Ears are moving up and to the side of the head eyes are moving closer together. External genitalia will develop into a recognizable penis or clitoris and labia majora.

4 weeks: The neural tube along your baby's back is now closed. Head, mouth, liver, and intestines begin to take shape.

Different SpeciesDifferent Species

Size Size

First trimester First trimester Mother’s symptomsMother’s symptoms

Secondary amenorrhea (spotting) Secondary amenorrhea (spotting) Morning sicknessMorning sicknessTenderness of breasts (darkening areola)Tenderness of breasts (darkening areola)Positive pregnancy test (hCG)Positive pregnancy test (hCG)Increase size abdomen Increase size abdomen Softening of the cervixSoftening of the cervixIncreased frequency of urinationIncreased frequency of urinationDetection of heart beatDetection of heart beatVisualization of the fetus (ultrasound)Visualization of the fetus (ultrasound)

2nd Trimester2nd TrimesterFingernails have grown on the tips of the fingers and Fingernails have grown on the tips of the fingers and toes, and the fingers and toes are fully separated. toes, and the fingers and toes are fully separated. The fetus goes through cycles of sleep and wakefulness. The fetus goes through cycles of sleep and wakefulness. Skin is wrinkly and red, covered with soft, downy hair Skin is wrinkly and red, covered with soft, downy hair (called lanugo). (called lanugo). Hair is growing on the head of the fetus. Hair is growing on the head of the fetus. Fat begins to form on the fetus. Fat begins to form on the fetus. Eyelids are beginning to open and the eyebrows and Eyelids are beginning to open and the eyebrows and eyelashes are visible. eyelashes are visible. Fingerprints and toeprints have formed. Fingerprints and toeprints have formed. Rapid growth is continuing in fetal size and weight. Rapid growth is continuing in fetal size and weight. The 20th week marks the halfway point of the The 20th week marks the halfway point of the pregnancy. pregnancy.

3th Trimester3th TrimesterBaby's eyes open Baby's eyes open Movement is more forceful Movement is more forceful Baby packs on pounds Baby packs on pounds Downy hair falls off Downy hair falls off Baby detects light Baby detects light Protective coating gets thicker Protective coating gets thicker Rapid growth continues Rapid growth continues Baby can suck Baby can suck Organ function continues to improve Organ function continues to improve Placenta provides antibodies Placenta provides antibodies

22ndnd-3-3rdrd Trimester TrimesterMother’s symptoms Mother’s symptoms

•Second trimester movement felt; heightened sense of well-being

•Third trimester increased size; greater discomfort

The Experience of PregnancyThe Experience of Pregnancy

For the manFor the man– ecstasy to ambivalence to fearfulnessecstasy to ambivalence to fearfulness– sense of separationsense of separation– concern about financial impactconcern about financial impact– active involvement helpsactive involvement helps

Sexual interaction during pregnancySexual interaction during pregnancy

– inhibited during 1st & 3rd trimesters; or inhibited during 1st & 3rd trimesters; or progressive declineprogressive decline

– some women experience increases in desiresome women experience increases in desire– no restrictions on sexual activity or orgasm no restrictions on sexual activity or orgasm

unless woman is at riskunless woman is at risk– modified positions often neededmodified positions often needed

Chromossomic Birth Defects Chromossomic Birth Defects

Rates increase with age of parents Rates increase with age of parents (particularly mother)(particularly mother) Example Down SyndromeExample Down Syndrome– 1/1000 before 35 years old1/1000 before 35 years old– 1/200 – 35 years old1/200 – 35 years old– 1/15 – 45 years old1/15 – 45 years old

Environmental Birth DefectsEnvironmental Birth DefectsMost substances are filtered by the placentaMost substances are filtered by the placenta

There are some exceptionsThere are some exceptions•Some virus (HIVSome virus (HIV•Some bacteria (Syphilis)Some bacteria (Syphilis)•Alcohol, cocaine, other drugsAlcohol, cocaine, other drugs

Fetal Alcohol Syndrome Fetal Alcohol Syndrome is the is the most common cause of most common cause of mental mental retardation in the US)retardation in the US)

The effect of those substances will depend The effect of those substances will depend of the structure developing at the time and of the structure developing at the time and the dose.the dose.

Some birth defects have being associated with malnutrition/ vitamin deficiency (Spina bifida)

Detection of birth defectsDetection of birth defects

Alpha-fetoprotein levelsAlpha-fetoprotein levels Acetylcholinesterase Acetylcholinesterase Estriol and beta-human chorionic Estriol and beta-human chorionic Inhibin A Inhibin A UltrasoundUltrasoundChorionic villus sampling (10 weeks)Chorionic villus sampling (10 weeks)Amniocentesis (14 to16 weeks)Amniocentesis (14 to16 weeks)

Labor first stageLabor first stageBegins with the onset of Begins with the onset of contractions and contractions and changes in the cervix and changes in the cervix and ends when your cervix is ends when your cervix is fully dilated.fully dilated.

This stage is divided into This stage is divided into two phases: two phases: – early (or latent) cervix early (or latent) cervix

gradually effaces (thins gradually effaces (thins out) and dilates (opens). out) and dilates (opens).

– active labor: cervix begins active labor: cervix begins to dilate more rapidly and to dilate more rapidly and contractions are longer, contractions are longer, stronger, and closer stronger, and closer together. together.

Labor Labor Second StageSecond Stage

begins once you're begins once you're fully dilated and ends fully dilated and ends with the birth of your with the birth of your baby. This is baby. This is sometimes referred to sometimes referred to as the "pushing" as the "pushing" stage. stage.

LaborLaborThird StageThird Stage

Begins right after the Begins right after the birth of your baby and birth of your baby and ends with the ends with the separation and separation and subsequent delivery subsequent delivery of the placenta. of the placenta.

MiscarriageMiscarriage

– occurs in first 20 weeksoccurs in first 20 weeks– emotional impact can be significantemotional impact can be significant– couple needs grief-support couple needs grief-support

AbortionAbortionElective Elective abortionabortion

Approximately Approximately 25% of U.S. 25% of U.S. pregnancies pregnancies end in elective end in elective abortion; 1% abortion; 1% occur after 20 occur after 20 weeksweeks

Elective abortion Elective abortion

– ProceduresProceduresmedical abortion (medication only until 7 weeks)medical abortion (medication only until 7 weeks)suction curettage in 90% of pregnancies in the USsuction curettage in 90% of pregnancies in the USdilation & evacuation dilation & evacuation late-term abortion procedureslate-term abortion proceduresillegal abortionsillegal abortions

Abortion controversyAbortion controversy

– historical overviewhistorical overviewEarly American law allowed abortion until Early American law allowed abortion until quickeningquickening1973 Roe vs. Wade 1973 Roe vs. Wade 1977 Hyde Amendment 1977 Hyde Amendment State restrictions or limitationsState restrictions or limitationsWaiting period, parent notificationWaiting period, parent notificationMexico City Policy (international gag order)Mexico City Policy (international gag order)

Abortion controversy (cont.)Abortion controversy (cont.)

– current debatecurrent debatemajority of Americans believe abortion should majority of Americans believe abortion should remain legalremain legalpro-life goalspro-life goalspro-choice goalspro-choice goalsrecent debate is more violentrecent debate is more violentethnic differences in views toward abortionethnic differences in views toward abortion

human pregnancy

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