Millions of sperm are deposited in the vagina during intercourse but only 50-100 of these reach the ovum. Conception normally occurs in the outer 1/3 of the Fallopian tube and cell division begins immediately. The morula (cell mass) enters the uterus some 3 to 4 days later. A few days after that the blastocyst (8-16 cells) is ready to implant into the endometrium. Some of these cellls develop into the fetal portions of the placenta while the others become the embryo. A Doppler ultrasound device can detect the baby’s heart sounds around 8-10 weeks and the heart sounds can be heard with a regular stethoscope at 18-20 weeks.
The first sign of pregnancy and the reason that most women seek a physician is when they are sexually active and have missed a period. Breast enlargement and tenderness, nausea and occasional vomiting may also be noticed. Blood or urine tests are done to confirm pregnancy. Many different urine pregnancy tests are available over-the-counter at local drug stores.
By convention, pregnancies are usually dated from the first day of the last menstrual cycle. Therefore, usually two weeks after missing a period, you are considered to be six weeks pregnant. Pregnancies are considered to last 266 days (38 weeks) after conception or 280 days from the last menstrual cycle (40 weeks). “Due Dates” are calculated by subtracting 3 months from the first day of the last menstrual cycle and adding 7 days. This is an approximate calculation and only about 10% of all babies are born exactly on their due date. A baby is considered full-term if it arrives any time +/- two weeks of their projected due date or 36-42 weeks gestation.
Pregnancy causes changes in every system in the body. However, these changes generally revert back to pre-pregnancy state about 6 months after the baby is born. One of the most common and uncomfortable changes takes place in the kidneys. The hormones, particularly progesterone, which the body produces during pregnancy, cause the ureters (tubes that carry urine from the kidneys to the bladder) to dilate allowing a greater amount of urine to make its way into the bladder in a shorter amount of time. This larger amount of urine combined with the pressure the baby is putting on the bladder results in a frequent need to urinate.
Another often noticed change occurs in the stomach. As the uterus enlarges, it compresses the stomach, slowing the speed at which the stomach empties. Hormones also cause the sphincter at the base of esophagus, which keeps food in your stomach, to relax. The combined result of both of these changes is that belching and heartburn may occur.
Melasma, the “mask of pregnancy” refers to a blotchy pigmented area on the forehead and sides of the face. This is possibly due to the placenta producing a melanocyte-stimulating hormone. The mask will generally fade away over time after the pregnancy.
During the pregnancy, the mother may experience nausea and vomiting, especially in the first trimester. No medications have been approved for this. If “morning sickness” occurs, a physician may have some suggestions as to its treatment. Eating and drinking frequently and in small amounts may help alleviate the problem.
Many other symptoms may be noticed. A physician should be consulted for questions and is the best source of information about the changes going on in the body.
Labor and Delivery
The cervix is normally firm in the nonpregnant state and through most of pregnancy. However, near the end of the pregnancy, the cervix softens and dialates. Once labor has begun, the uterine contractions dilate the cervix more and this dilation sends signals to the brain to increase oxytocin release. The increased oxytocin acts on the uterus to increase the force of contractions and also causes the production of prostaglandins in the uterine lining and placenta. The prostaglandins further increase uterine contractions. These mechanisms aid in delivery of the baby and expulsion of the placenta. Delivery is aided by spinal reflexes and voluntary contractions of the abdominal muscles as well.
A physician will generally explain what to expect during labor and delivery. It is often helpful to attend a birthing class.
Lactation as birth control
In the case of “unwanted pregnancy”, women should consider providing the baby to an adoption service for placement with a family desiring to nuture a new baby. By so doing, one individual’s “problem” can be turned into a blessing for another couple.