One test that has been used to determine pregnancy uses blood or urine samples to detect a hormone known as BhCG, found exclusively in pregnant women. Later, prenatal diagnostic tests such as alpha fetoprotein, amniocentesis , and chorionic villus sampling may be performed as screening measures for congenital defects. Ultrasound , a sonar device using high-frequency wavelengths, is used to detect defects, measure fetal heartbeat, and monitor growth of a fetus.
Complications of pregnancy include eclampsia , premature birth, and erythroblastosis fetalis (Rh incompatibility). Ectopic pregnancy, in which the fetus begins to develop outside the uterus, often in a fallopian tube , is another complication. It is often the result of scarring from a sexually transmitted disease . Smoking has been linked to low–birth weight infants; alcohol consumption during pregnancy has been linked to a group of defects called fetal alcohol syndrome .
The technology relating to pregnancy has made great advances and has created a number of ethical issues. Many women in their 40s are now able to sustain successful pregnancies, due to technological devices that carefully monitor the progress of the fetus. In vitro fertilization and other infertility treatments have allowed even postmenopausal women to give birth. The use of fertility drugs has led to a marked increase in multiple births . Abortion , in which pregnancy is terminated prior to birth, has long been a subject of heated debate, and surrogate motherhood (see surrogate mother ) has also raised ethical issues in recent years.
See J. T. Queenan and C. N. Queenan, ed. A New Life (1992); C. A. Bean, Methods of Childbirth (1990);; Boston Women's Health Book Collective, Our Bodies, Ourselves for the New Century (1998).
The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.
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