Welcome to Baby Making 101

Pregnancy and Embryonic Development A. Accomplishing Fertilization 1. oocyte viable for 12-24 hours after ovulation 2. sperm is viable for 12-48 (sometimes up to 72) hours after ejaculation. Takes 1-2 hours to swim length of fallopian tubes

b. generally occurs in upper 1/3 of fallopian tubes 3. fertilization – moment genetic material of sperm combines with genetic material of ovum to form zygote a. in order to achieve fertilization, sex may occur no more than 72 hours before ovulation and no more than 24 hours later. b. generally occurs in upper 1/3 of fallopian tubes c. requires several sperm to “clear a path” through corona radiata

B. Events of Embryonic and Fetal Development 1. after 3 days of cell division (cleavage) zygote is now a morula (solid ball of 16 cells) 2. continued divisions result in blastocyst (hollow ball) which implants itself in the uterine wall 10 days after fertilization

3. blastocyst secretes HCG (Human. Chorionic Gonadotropin) causing 3. blastocyst secretes HCG (Human Chorionic Gonadotropin) causing the corpus luteum to produce progesterone, which in turn maintains uterine lining 4. three germ layers have now formed (day 7) a. ectoderm – gives rise to nervous system and epidermis b. mesoderm – everything in between c. endoderm – mucosae and associated glands

5. by day 14 implantation is. complete and uterine mucosa 5. by day 14 implantation is complete and uterine mucosa has grown over embryo 6. blastocyst develops projections (chorionic villi) together with mother’s tissue make up the placenta 7. embryo surrounded by amnion and is attached to placenta by the umbilical cord (functional during third week)

8. by week eight: a. all systems developing b. embryo looks human c. umbilical cord producing estrogen and progesterone to maintain uterine lining; corpus luteum becomes inactive 9. by week nine: a. embryo now referred to as fetus b. major activities are growth, organ specialization, and developing body proportions

10. “Fetal Development Period” – from 9th week on a. growth from 1 to 14 inches (crown to rump) b. weight gain from .03 ounces to 6-10 pounds c. at birth total body length (head to foot) is about 22 inches 11. fetus is “full term” 270 days after fertilization – the end of the 10th lunar month

C. Effects of Pregnancy on the Mother 1. Anatomical changes a. growth of uterus 1. pushes into abdominal cavity 2. by birth has reached level of xiphoid process 3. causes abdominal organs to press superiorly against diaphragm; ribs flare and thorax widens b. center of gravity change can bring on lordosis and accompanying backaches

c. placental production of relaxin. causes pelvic ligaments and c. placental production of relaxin causes pelvic ligaments and pubic symphysis to relax and widen, causing waddling gait d. substances to avoid include alcohol (FAS), nicotine, anticoagulants, antihypertensives, sedatives, some antibiotics; German measles (rubella virus) can also cause severe fetal damage

2. Physiological changes a. gastrointestinal system 1. morning sickness due to elevated hormone levels 2. heartburn 3. constipation b. urinary system 1. increased urine production 2. frequent, urgent, and uncontrollable urination

c. respiratory system 1. nasals stuffiness and nose bleeds – estrogen’s effect on nasal mucosa 2. breathing becomes difficult and respiratory rate increases d. cardiovascular system 1. blood volume increases 25-40% 2. BP and pulse increase 3. varicose veins may develop

D. Childbirth (parturition) – within 15 days of due date, 280 days from last menstrual period 1. initiation of labor a. estrogen levels increase last few weeks 1. myometrium becomes sensitive to oxytocin 2. oxytocin interferes with progesterone’s quieting effect on uterine muscle; can cause Braxton Hicks contractions or false labor

b. fetal cells producing. oxytocin and the placenta b. fetal cells producing oxytocin and the placenta releasing prostaglandins stimulate powerful contractions c. mother’s physical and emotional stress stimulates the hypothalamus which in turn stimulates the posterior pituitary to increase oxytocin production d. increased oxytocin combined with prostaglandins initiates true labor

e. positive feedback loop. established between e. positive feedback loop established between contractions and oxytocin f. Aspirin/ibuprofen inhibit release of prostaglandins in early stages of labor; may be used to prevent premature births

2. stages of labor a. stage 1: Dilation – from start of true contractions until full cervix dilation (10 cm) 1. longest stage: 6-12 hours 2. contractions strengthen and become regular 3. each contraction forces baby’s head against cervix 4. amnion ruptures (water breaks)

b. stage 2: Expulsion – from full dilation to delivery 1. as long as 2 hours, normally around 50 minutes with first birth and 20 minutes with each subsequent birth 2. vertex – head first advantages: skull acts as a wedge, allows for suctioning of mucus, baby can breath earlier breech – buttocks first 3. cesarean section (C-section) – performed as a result of prolonged stage 2 labor, breech, or other problems

c. stage 3: Placental – delivery of placenta 1. 15 minutes after birth 2. afterbirth – placenta and attached fetal membranes 3. delivery of placenta prevents postpartum bleeding

E. Disorders of Pregnancy 1. Implantation disorders a. Ectopic pregnancy – embryo implantation outside of uterus b. Placenta previa – growth of placenta at or near the cervical opening, often results in separation of the placenta from the uterine wall c. Abruptio placentae – separation of a normally placed placenta from the uterine wall

2. Preeclampsia (toxemia of. pregnancy) – syndrome that 2. Preeclampsia (toxemia of pregnancy) – syndrome that includes hypertension, proteinuria (large amounts of protein in urine – can be due to hypertension), and edema; may progress to eclampsia – severe toxemia that may result in death 3. Fetal death a. spontaneous abortion – 12- 20 weeks (miscarriage before 12 weeks) b. stillbirth – after 20 weeks

4. Birth defects/congenital abnormalities – acquired or inherited 5. Postpartum disorders a. Puerperal fever – caused by bacterial infection and may progress to septicemia and death b. Lactation complications brought on by anemia, malnutrition, or other factors that in turn disrupt infant nutrition 1. Mastitis – inflammation/ infection of the breast 2. Lactose intolerance – inability to digest milk c. Depression