The U.S. Centers for Disease Control and Prevention notes that 10.9 percent of women ages 15 through 44 struggle with impaired fertility. Dealing with infertility often means needing help to conceive. In the past four decades 36 percent of twin and 77 percent of triplet or more births have been from the use of fertility treatments, according to the "New England Journal of Medicine."
In Vitro Fertilization
During a woman's normal menstrual cycle only one egg -- in most, but not all, cases -- is released. Using in vitro fertilization as a fertility treatment may mean implanting more than one embryo in the woman's uterus to raise the chances of a successful pregnancy. The CDC notes, in the "2011 Assisted Reproductive Technology: Fertility Clinic Success Rates Report," that roughly two embryos were transferred per mother during IVF procedures. The more embryos implanted, the higher the odds are of having multiples, according to the Center for Human Reproduction.
Even though the rate of having multiples is higher when using an assisted fertility treatment than conceiving naturally, the trend is gradually lowering. According to the "New England Journal of Medicine," there was a 29 percent decrease in triplet or higher multiple births from fertility treatments between 1998 and 2011. The reason behind this trend seems to come from the reduction of embryo transfers during IVF procedures.
Controlled Ovarian Hyperstimulation
Controlled ovarian hyperstimulation is another fertility treatment that women may try. During COH the woman gives herself hormone shots to stimulate ovulation. Although COH doesn't necessarily create multiple embryos in the same way that IVF does, it can lead to the release of multiple eggs during a single cycle, according to the University of Wisconsin Hospitals and Clinics. Ovulating more than one egg increases the chances of conceiving multiples.
The multiple births that may result from fertility treatments can put the mother at risk of complications. Carrying more than one baby may result in anemia, gestational diabetes, increased blood pressure, pre-eclampsia and the possibility of preterm labor, notes the University of Wisconsin Hospitals and Clinics. The risks associated with carrying multiples are a primary reason for doctors increasingly advocating to insert fewer embryos during any given fertility treatment cycle.
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