Twin Birth: Why the Uproar?

As the twin birth rate increases, so does health risk and cost


The Center for Disease Control (CDC) and Prevention’s National Center for Health Statistics (NCHS) just issued a brief regarding a large increase in twin births in the US over the last three decades. Thirty years ago, about one in 50 babies was a twin. Now, the number is 1 in 30. The rate of twin births in women aged 35 to 39 has almost doubled, and rose 200 percent in women age 40 and above.

The rate of twin birth rises naturally with mother’s age, which has been rising in recent decades. The report states, however, that the increase overall is mostly due to use of fertility therapies.

The reports cite the increased health risks and health care costs associated with twin birth. The major health issues for twins are prematurity and low birth weight. About half of twin births are premature and/or “low birth weight”, increasing the baby’s chance of short-term or long-term problems. About 10 percent of twins are “very low birth weight,” and these infants have very high risk of problems, or even death.

Faced with the choice of twin birth or no birth, most infertile couples choose to take their chances with twins. Occasionally, couples express a preference for twins, citing their desire to be done with the arduous fertility experience. Others recognize that their chances are limited by the women’s age. Older women (age 38 and older for most women) have a lower chance of success with fertility therapy. Therefore, the woman may not desire twins, but understands that her chances of having a baby a few years from now will be even lower than they are now.

The rate of twin conception varies dramatically by the type of fertility therapy and the age of the woman. Simple fertility medications such as Clomid typically have approximately 10 percent twin rate, which decreases with a woman’s age. Stronger fertility drugs are associated with a higher rate of twins, and even triplets, etc.

With In Vitro Fertilization (IVF), the rate of multiples can be controlled by the number of embryos transferred. But even this isn’t perfect since the rate of an embryo implanting (becoming a fetus in the uterus and ultimately, a baby) varies from 70 percent for perfect embryos in young women, to less than 10 percent per embryo in women over 40.

What’s a couple/woman to do? Speak to a reproductive endocrinologist about your concerns and motivations.