Why do twins and triplets increase suddenly?

The rate of twins and triplets in the United States has increased dramatically since 1980 and this phenomenon was ultimately determined by artificial interventions.

The rate of twins and triplets in the US surged unexpectedly

According to the report of the Centers for Disease Control and Prevention (CDC), the proportion of twins in the country has increased by nearly 80% since 1980. The rate of triple births, even births and highs. more also increased significantly, nearly 4 times in the same period.

Some researchers even call the phenomenon of skyrocketing multiple births as "translated".

Studies show that high rates of multiple births in the United States are due to many women delaying childbirth and using reproductive treatments , such as in vitro fertilization (IVF) when they want to have a baby. In 2011 alone, up to 36% of twins in the country were the result of conception with medical help.

When a woman relies on IVF for conception, one or more embryos will be fertilized in the laboratory, then implanted in her uterus in the hope that at least one of them will be able to hold on. and grow into a child. To increase the likelihood of the woman "sticking" , doctors often implanted more than one embryo into her uterus. This approach also increases the probability that a woman will carry more than one pregnancy and then have multiple pregnancies.

Experts know this risk well, but cannot completely avoid it. As the researchers wrote in The New England Journal of Medicine : "Although the introduction of three or more embryos in an IVF cycle has decreased, many factors can curb efforts to reduce numbers. more workpieces ".

The graph shows the rate of multiple pregnancies in the US since 1980.

However, so far, experts have not determined exactly which stage in the process of assisted reproduction is making the number of twins increase dramatically. According to the American Society for Reproductive Medicine, the use of ovulation stimulants is a "culprit" that increases the majority of multiple pregnancies . Usually, every month, only one egg in a woman's ovaries is ready to fertilize, but the drug stimulates the ovaries to have more than one egg ready to "meet" the sperm. With more eggs ready to fertilize, women are also more likely to have multiple pregnancies.

In addition, although fertility generally decreases with women's age, the rate of multiple births is higher in older women . In the United States, according to the CDC, the birth rate increases for women over 30 years old and this may also be related to the increasing rate of multiple births in the country.