1. Childbirth and Contraception Campbell pages 992-995

2. So, 9 months later … During pregnancy, progesterone inhibits the secretion of oxytocin (hormone) by the pituitary gland –Remember, we want high levels of progesterone to maintain pregnancy At the end of pregnancy, hormones send signals to the placenta to stop secreting progesterone

3. (Cont.) Estrogen reaches its highest level at the end of pregnancy –Triggers the formation of oxytocin receptors on the uterus Oxytocin –Produced by the fetus and the mother’s pituitary gland –Stimulates contractions of the uterus –Stimulate the placenta to secrete prostiglandins, which enhance the contractions –Positive feedback mechanism (more hormones are released)

4. My water just broke … now what? The contractions cause the amniotic sac to burst (amniotic fluids are released) –Amniotic sac supports and protects the fetus 3 phases of birth: –1. opening up and dilation of the cervix –2. delivery of the baby The umbilical cord is cut and clamped –3. delivery of the placenta

5. Breast Feeding The decrease in progesterone allow for the secretion of prolactin –Prolactin stimulates milk production after a delay of ~2-3 days –The release of milk if controlled by oxytocin

6. So now that I know how to get pregnant, how can I prevent it? Contraception: deliberate prevention of pregnancy Methods: –1. Abstinence –2. Rhythm method No sex days before or after ovulation Monitor changes in cervical mucus and body temperature Also used to increase chance of pregnancy

7. More methods 3. Condom –Used by male –Latex; fits over erect penis to collect semen –Spermicidal foam or jelly 4. Diaphragm –Dome shaped rubber cap fitted into the upper portion of the vagina –Spermicidal foam or jelly

9. More methods 5. IUD –Intrauterine device –Fit into the uterine cavity –Prevent implantation of the blastocyst –Harmful effects (bleeding, infection, tubal pregnancy 6. Pulling out –Man “pulls out” before ejaculation –Unreliable

11. More methods 7. Birth Control Pill –Combinations of estrogen and progesterone –Stop the release of LH and FSH –Blocking LH prevents ovulation –Blocking FSH prevents the follicle from forming –High levels of estrogen causes the uterine lining to thicken, so a female still gets her period –Highly effective; safety is debated Blood clots, heart attacks; smoking increases these risks 8. Sterilization –Vasectomy (vas deferens is cut) –Tubal ligation (oviducts are cut)

12. Safe sex Condoms are the only form of contraception that offer protection from STD (STI) and HIV/AIDS