Seeing double? The public health impact of twins

A Post by: Ellaheh Gohari

April 3, 2023

In the immortal words of Team Rocket: “Prepare for trouble… and make it double!” Though most human pregnancies only involve a single baby, twins — or when the same pregnancy results in two fetuses — occur naturally in about one in 250 pregnancies. The more fetuses, the less common: the rate of triplets is one in 10,000, and the rate of quadruplets is one in 700,000.

In the United States, however, the rate of twins has skyrocketed, increasing a whopping 76% since 1980 after staying relatively stable for decades. In 2009, one of every 30 infants born in the US was a twin, and though this number reached its peak in 2014 before dropping slightly, it seems to be making a comeback once again.

Why the large increase? Fertility drugs, which have become more common in the past three decades, increase the rate of fraternal multiples as they stimulate hyper-ovulation, or the production of multiple eggs during one menstrual cycle. Similarly, in-vitro fertilization (IVF) — which was first used in 1978 — has also become relatively popular in the United States, accounting for nearly 1 million births between 1978 to 2015. IVF increases the rate of multiples because it often implants several embryos in order to have the highest chance of a viable fetus; if two or more of them are viable, then fraternal multiples might be born 9 months later.

This increased rate of twins/multiples is important in a public health context because these pregnancies are high-risk, particularly the more fetuses there are. Twins and other multiples tend to have lower birth weight, be born prematurely, and have birth defects like gastrointestinal and heart abnormalities. Often, triplet or higher multiples must spend time receiving care in a Neonatal Intensive Care Unit (NICU) as they were born too early to function independently. The mother may also be at risk due to an increased risk of hemorrhage as the uterus will have been stretched more than in a normal pregnancy.

Not only do these complications put personal strain on the families, in a global health context, it also puts pressure on the medical system to accommodate these patients. While improvements in neonatal care give once-considered-unviable infants the chance to live, there is still work to be done to ensure the continued survival of multiple births. Luckily, just by looking in the past two years, we can see the effects of medical advancements in action. For the first time in history, nonuplets were born to a Malian couple in 2021, with all nine babies surviving their first birthday.

Ultimately, it is important to continue striving for better care and management of multiple pregnancies to improve outcomes for all involved. Public health efforts should focus on ensuring that women who are pregnant with multiples receive appropriate prenatal care and monitoring to reduce the risk of complications. The goal is to improve the outcomes for both the mother and infants, which in turn will reduce the burden on healthcare systems and promote better health outcomes for families.