Twins

Newspaper Column Ad Appearing 5-14-03

Most often, conception involves the fertilization of one egg by one sperm, resulting in a singleton pregnancy. Seven out of 10 pairs of twins are the result of the woman having released two eggs, which are fertilized independently by two different sperm (fraternal twins). The two eggs then implant and develop separately in the uterus. Less commonly, one egg fertilized by one sperm divides, which results in two developing babies with the same inherited characteristics (identical twins). Mothers who are fraternal twins themselves are about twice as likely to give birth to twins as other women. The chances of having fraternal twins depend on heredity, age, race, and the number of children already born. The frequency of identical twins seems independent of these variables.

However, recent increase in the frequency of twins and higher order multiple pregnancies may be attributed to the use of fertility drugs. Fertility drugs stimulate development and release of more than one egg which may then fertilize and develop into fraternal twins, triplets, or higher order multiples. The risk of multiple pregnancy is much higher when fertility drugs are used (the number of released eggs frequently cannot be controlled) than with in vitro fertilization/embryo transfer (IVF/ET) when a predetermined number of embryos (one, two, but not more than three) are placed in the uterus.

If you think there is an increased chance that you will have twins (or more) because of family history or your use of fertility drugs, see your obstetrician as soon as you suspect you may be pregnant. The more the merrier, but also the greater the risk. You will want to have your pregnancy more closely monitored by your doctor. For additional information on this subject or to schedule an appointment, please telephone OAK BROOK FERTILITY CENTER, a medical practice devoted to reproductive endocrinology, infertility, and assisted reproductive technology. New patients are welcome.

P.S. Identical twins almost always share a placenta, though each has its own cord and water bag. Fraternal twins have separate placentas, water bags, and cords.

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