Labor and Birth In-class activity

Labor and Birth In-class activity T/F; daily folic acid in multivitamin reduced development of neural tube defects in infants - true T/F: weight gain of at least 25 lbs is recommended for pregnant women - true Sources of weight gain in pregnant women - maternal fat breast and uterine growth placenta amniotic fluid increased maternal blood volume fetus is on avg 7.5 lbs at birth Physiological changes in pregnant women - increased blood volume, cardiac output/volume of blood, heart rate, kidneys increase in size and increase filtration rate by 50%, increased respiratory rate with increased ratio of O2/CO2 which facilitates transfer of O2 to and removal of CO2 from fetal blood through placenta Maternal complications of pregnancy - toxemia (preeclampsia & eclampsia) Toxemia - develops in last 2 months of pregnancy in 6-7% of pregnancies in US Preeclampsia - early toxemia weight gain edema (fluid accumulation in tissues) high blood pressure proteinuria (protein in urine) Eclampsia - severe toxemia similar symptoms as preeclampsia, with convulsions, coma, death Maternal complications of pregnancy: gestational diabetes mellitus - occurs in 1% of pregnancies as some pregnant women gain weight their tissues develop resistance to insulin, resulting in significant rise in maternal and fetal glucose levels higher glucose levels in fetus cause them to grow unusually large (macrosomia) which makes vaginal delivery hard Ectopic pregnancy - implantation in oviduct implanted embryo not able to develop into viable fetus, puts mother's health and life in danger, requires surgical removal of embryo and placenta Endocrinological changes in pregnant women - implantation induces corpus luteum to continue functioning and produce progesterone and estrogen during first trimester, helps maintain development of placenta steroids from corpus luteum in early pregnancy supports maternal appetite, fat deposition, breast growth secretion of hCG by cells of cytotrophoblast starts as soon as 2 days after implantation hCG contributes to persistence of corpus luteum through 1st trimester after 5th week of pregnancy, hCG in placeta stimulates placenta to secrete progesterone as well as estriol, estradiol, estrone for hormonal support Endocrinological changes in pregnant women and fetus - secretion of estrogens by placenta require intermediate steps in fetal adrenal gland/liver mother provides cholesterol to placenta (which makes progesterone), supplied to fetus and mother progesterone made by placenta reaches fetal adrenal glands (called fetal zone), where it is converted to weak androgen (DHEA) which is then converted in fetal liver to 16-OH DHEA-sulfate and is transferred back to placenta where it's converted to estriol Placenta also produces hormones similar to ones made by pituitary - prolactin corticotropin thyrotropin endorphins oxytocin human placental lactogen (hPL) - placenta secretes hPL, has effects similar to growth hormone and prolactin hPL particularly high in maternal blood late in pregnancy, which sightly increases maternal and fetal blood glucose hPL (with progesterone and estrogen) also helps prime mammary glands for milk production Relaxin - secreted by corpus luteum and placenta, levels rise steadily during pregnancy relaxes connective tissue connecting 2 pubic bones (pubic symphysis) so that fetus can pass through birth canal more easily at delivery prepares cervix to soften and dilate before and during labor human labor/birth initiation - increase relaxin, CRH (corticotropin releaseing hormone), cortisol, estrogen/progesterone ratio, prostaglandins, oxytocin T/F: CRH from fetal brain/ placenta is likely signal for beginning for labor - true 3 positive feedback systems tha help maintain labor - CRH-fetal pituitary-fetal adrenal axis oxytocin and myometrial contractions production of prostaglandins by contracting uterus CRH levels and time of birth - levels in weeks 16-20 can help predict time of birth, women with lower levels tend to delivery post term, women with normal levels tend to delivery at term, women with high levels tend to delivery pre-term Human labor/birth initiation: increase CRH - increased CRH production from placenta results in: increased fetal cortisol production (+ feedback loop) increased maturation of fetal organs in prep for birth increased uterine prostagladin production (+ feedback) increased estrogen/progesterone ratio in maternal blood HUman labor/birth initiation: cortisol - increased cortisol from fetal adrenal glands causes + feedback loop with CRH, this stimulates fetal pituitary gland to produce acth to stimulate fetal adrenal gland to produce more cortisol cortisol released from fetal adrenal glands appears to contribute to initiation of labor Human labor/birth initiation: increase estrogen progesterone ratio - CRH directly acts in fetal zone of fetal adrenal gland to induce DHEA prouction which leads to more estrogen production by placenta increase in estrogen/progesterone ratio in last 5 weeks of pregnancy can help initiate labor increased estrogen supports increased uterine contractility Human labor/birth initiation: prostaglandins - increase during last month of pregnancy and directly stimulate uterine (myometrium) contraction CRH stimulates production of prostaglandins from fetal membranes high levels of prostaglandins have + feedback with CRH production by placenta increased estrogen/progesterone ratio stimulates prostaglandin production Human labor/birth initiation: oxytocin - oxytocin has strong stimulatory effect on uterine contractions through positive feedback mechanism secreted by posterior pituitary gland, probably by placenta increased estrogen/progesterone ratio appears increase oxytocin secretion and increase oxytocin receptors in uterus uterine contractions then stimulate more oxytocin production oxytocin also appears to stimulate increased prostaglandin production from uterus Fetal ejection reflex - stimulation of oxytocin release by mechanical stimulation of uterus, cervix or vagina, resulting in further uterine contractions