Illustration of human conception: the egg is expelled from the ovary and becomes susceptible to fertilization (penetration) by sperm (top). The sperm penetrates the egg (middle), and the fertilized egg (conceptus) travels down the fallopian tube to implant in the uterus (bottom).

Illustration of a generic 28-day birth control pill packet and how it works. The birth control pill is the most effective contraceptive; its hormones change the cervical mucus to make it hostile to sperm and alter the uterine lining to prevent implantation of the fertilized egg. Most birth control pills also prevent egg release from the ovary.

Illustration of various contraceptive methods (not including the birth control pill): intrauterine device (IUD) (top left), diaphragm (top right), condom (bottom left), and spermicidal foam (bottom right).

Illustration of amniocentesis, in which a sample of amniotic fluid is removed and tested to detect fetal age and sex, chromosome abnormalities (a chart of normal female chromosomes is shown, top right), neural tube defects, inherited diseases, and fetal Rh factor sensitization. Risks include infection, membrane rupture, fetal injury, and premature labor.

Illustration of a normal vaginal birth. Also shown (top right) is the location of an episiotomy (dashed line), which may be performed during the birthing process to prevent tearing of the perineum or to enlarge the vaginal opening to speed delivery.

Illustration of a cesarean (c-) section (birth), in which a doctor delivers the baby through incisions in the lower abdomen and uterus. Reasons for a c-section include improper positioning of the fetus, too large a head, ineffective contractions, or a previous c-section. The illustration shows a vertical skin incision and transverse uterine incision.

Conceptual illustration of immature labor. Shown are the fetus, placenta (at the top of the uterus), umbilical cord, uterus, bulging of the amniotic sac, and dilation of the cervix. The degree of prematurity affects neonatal morbidity and mortality and the extent of potentially long term health problems.

Illustration of an ectopic pregnancy. Shown are a normal fallopian tube (left) and an ectopic pregnancy in a fallopian tube (right). An ectopic pregnancy occurs when a fertilized egg attaches and begins to develop outside the uterus. Ectopic pregnancies occur in the fallopian tube, ovary, or cervix (other places are rare). Most spontaneously miscarry.

Illustration of cervical cerclage, a surgery used to keep an incompetent cervix closed during pregnancy. Shown are the area of treatment (top), before treatment view (left), and after treatment view (right), with the vaginal mucosa at the anterior lip of the cervix. It is also known as tracheloplasty, shirodkar, lash type, or McDonald's purse string.

Illustration of six states of a normal uterus. Shown are (from the top, left to right): nonpregnant uterus; pregnant uterus at term; pregnant uterus at term with mucous plug; uterus beginning labor with dilation of the cervix; uterus with amniotic fluid coming out (water breaking); and uterus in labor with full dilation.

Illustration of a dilation and curettage (D&C) procedure, in which the cervix is dilated so that an instrument can be inserted to scrape or suction the lining of the uterus and take tissue samples. Shown on this abnormal uterus are intramural and submucous fibroids and polyps.

Illustration of a diagnostic laparoscopy. Shown are broad cutaway (top) and close up (bottom) views that depict the laparoscope, fallopian tube, fibria, ovary, and uterus.

Illustration of an abdominal hysterectomy, a surgical removal of the uterus through an incision in the abdominal wall. The illustration shows two steps: 1) before removal, with surgical clamps (top); and 2) after removal, showing the closure of the vagina with sutures (bottom).

Illustration of a vaginal hysterectomy (top) and a vaginal repair of a cystocele, also called a fallen bladder (bottom, two steps left to right). A vaginal hysterectomy is a surgical removal of the uterus through an incision within the vagina that leaves no external scar. The vaginal repair treats the involuntary loss of urine caused by cystocele.

Illustration of an ovarian cystectomy, a surgery to remove an ovarian cyst. Shown are an ovarian cyst in the left ovary (top), a dissection of the cyst from the ovary (middle), and the subsequent repair and closure of the ovary (bottom left).

Illustration of laser surgery to precisely remove abnormal tissues from the cervix (sparing normal tissue). Shown are the procedure (background) and the cervix (enlarged inset) with lesions before surgery (left) and three weeks after surgery (right).

Illustration of a conization (cone biopsy or cold knife cone biopsy) of the cervix, a procedure used to detect and treat abnormalities of the cervix, such as cervical neoplasia and cervical cancer. Shown are a cross section of the cone to be analyzed (top left), the procedure using a scalpel (middle), and the conical section removed from the cervix (bottom).

Illustration of a postcoital test (bottom left), blood hormone test (bottom middle), and endometrial biopsy (bottom right). The basal body temperature record (top) shows bold bullets at the typical times for the tests (postcoital test during ovulation and endometrial biopsy just before menstruation). These tests can evaluate infertility and diagnose cancer.

Illustration of hysterosalpingography (HSG), a test that examines the inside of the uterus and fallopian tubes. In this procedure to evaluate infertility, a contrast dye is injected into the uterus (top) and continuous x-rays (bottom) are taken as the dye flows into the fallopian tubes to detect injury, blockage, or abnormalities that prevent pregnancy.

Illustration of a myomectomy (cutaway view), the surgical removal of fibroids from the uterus that allows the uterus to remain in place, thus preserving fertility. Myomectomy methods include hysteroscopy, laparoscopy, and laparotomy.