Contraception and the Mammary Glands Aaron Z Keiah T Ryan G

Contraception Contraception is the deliberate prevention of pregnancy. It can be achieved in a number of ways. Some contraceptive methods prevent the release of mature eggs (secondary oocytes) and sperm from gonads, others prevent fertilization by keeping sperm and egg apart, and still others prevent implantation of an embryo. Pregnancy rate is the percentage of women using a particular family planning method who become pregnant during one year. Methods that prevent the release of gametes are the most effective forms of birth control.

Types of Contraception Fertilization can be prevented by abstinence or by any of several barriers that keep live sperm from contacting the egg. Rhythm method, or natural family planning, depends on refraining from intercourse when conception is most likely. The egg can survive in the oviduct for 24 to 48 hours and sperm for up to 72 hours, thus intercourse should be during several days before and after ovulation. Timing ovulation can be done using several indicators such as changes in cervical mucus and body temperature during the menstrual cycle. Pregnancy rate is 10-20%

Types of Contraception Coitus interruptus, or withdrawal, is the removal of the penis from the vagina before ejaculation. This is an unreliable method because sperm may be present in secretions that precede ejaculation, and a lapse in timing or willpower can result in late withdrawal.

Types of Contraception The several barrier methods of contraception that block the sperm from meeting the egg have pregnancy rates of less than 10%. The condom used by the male (2%), is a thin, latex rubber or natural membrane sheath that fits over the penis to collect the semen. For sexually active individuals, latex condoms are the only contraceptives that offer some protection against STIs, including AIDS. The barrier device most commonly used by females is the diaphragm (6%), a dome-shaped rubber cap fitted into the upper portion of the vagina before intercourse. Both the male condom and diaphragm are most effective when used with a spermicidal foam or jelly. Other devices include the cervical cap (14%), which fits tightly around the opening of the cervix and is held in place for a prolonged period by suction, and the vaginal pouch, or “female condom.” (5%)

Contraception Chemical contraceptives, most often used in the form of birth control pills, have pregnancy rates of less than 1%. The most commonly used birth control pills are a combination of a synthetic estrogen and a synthetic progestin (progesterone-like hormone). This combination acts by negative feed back to stop the release of GnRH by the hypothalamus and thus of FSH and LH by the pituitary. The prevention of LH release prevents ovulation. As a backup mechanism, the inhibition of FSH secretion by the low dose of estrogen in the pills prevents follicles from developing. A similar combination of hormones is available as an injection, in a ring inserted into the vagina, and as a patch. Combination birth control pills can be used in high doses as morning-after pills (MAPs). Taken within 3 days of unprotected intercourse they prevent fertilization or implantation with an effectiveness of about 75%.

Contraception A second type of birth control pill, called the minipill, contains only progestin. It does not effectively block ovulation, and it is not as effective as a hormonal combination. The minipill prevents fertilization mainly by causing thickening of a woman’s cervical mucus so that it blocks sperm from entering the uterus. The progestin causes changes in the endometrium that interferes with implantation if fertilization occurs. Progestin can be administered in time-release, match- sized capsules that are implanted under the skin and last for five years or by injections for three months, as well as in tablet form.

Hormonal Contraceptives Side effects for women taking a combination version, cardiovascular problems are the most serious concern. Birth control pills slightly raise a woman’s risk of abnormal blood clotting, high blood pressure, heart attack, and stroke. Smoking while using a chemical contraception increases the risk of mortality tenfold. Not only does it eliminate the dangers of pregnancy, women on birth control pills have mortality rates about one-half those of pregnant women. The pill also decreases the risk of ovarian and endometrial cancers and benign breast disease.

Contraception Sterilization is almost 100% effective. Sterilization is the permanent prevention of gamete release. Tubal ligation in women usually involves cauterizing or tying off (ligating) a section of the oviducts to prevent eggs from traveling into the uterus. Vasectomy in men is the cutting of each vas deferens to prevent sperm from entering the urethra. Both male and female sterilization procedures are relatively safe and free from harmful effects. Both are also difficult to reverse, so the procedures should be considered permanent.

Contraception Abortion is the termination of a pregnancy in progress. Spontaneous abortion, or miscarriage, is very common, occurring in one third of all pregnancies and often before the woman is even aware that she is pregnant. Each year about 1.5 million women in the U,S, choose abortions performed by physicians. A drug called mifepristone, or RU486, developed in France, enables a woman to terminate pregnancy nonsurgically within the first 7 weeks. RU486 blocks progesterone receptors in the uterus, thus preventing progesterone from maintaining pregnancy. It is taken with a small amount of prostaglandin to induce uterine contractions.

Reproductive Technology Amniocentesis and chorionic villus sampling are invasive techniques in which amniotic fluid or fetal cells are obtained for genetic analysis. Non invasive procedures usually use ultrasound imaging to detect fetal condition. A blood sample from the mother yields fetal cells that can be identified with specific antibodies and then tested for genetic disorders. Diagnosing genetic diseases in fetuses poses ethical questions. Parents may be faced with difficult decisions about whether to terminate a pregnancy or cope with a child who may have profound defects and a short life expectancy.

Mammary Glands Mammary glands are present in both sexes but normally function only in women and are important to mammalian reproduction. Within the glands, small sacs of epithelial tissue secrete milk, which drains into a series of ducts opening at the nipple. Fatty tissue forms the main mass of the mammary gland of a nonlactating mammal. The low level of estrogen in males prevents the development of both the secretory apparatus and the fat deposits, so male breasts remain small and the nipples are not connected to the ducts.