How to have twins: Factors, odds, and improving your chances

According to the ASRM, women who are themselves nonidentical twins produce twins in around 1 in every 60 births. For men who are nonidentical twins, the chance of conceiving twins is only 1 in every 125 births.

Some people believe that twins can skip a generation, meaning that a person will potentially have twins if one of their grandparents did. However, there is little evidence to support this theory.

Fertility treatment

The ASRM note that the main factor that increases the chance of having twins is the use of fertility treatments. The various types of fertility treatment available increase the likelihood of twins in different ways.

Some fertility drugs work by stimulating a woman’s ovaries, which can sometimes cause them to release more than one egg. If sperm fertilizes both of these eggs, this can result in twins.

In vitro fertilization (IVF) can also increase the chance of conceiving twins.

Healthcare professionals carry out IVF by extracting a woman’s eggs and fertilizing them with a donor’s sperm in a laboratory to produce an embryo. They then transfer the fertilized embryo into the woman’s womb.

To increase the likelihood of success, the healthcare professional may place more than one embryo into the womb. Twins can occur if both embryos implant and develop successfully.

Multiple pregnancies carry additional risks, so the healthcare professional will usually limit the number of embryos that they transfer to the woman’s womb to reduce the chance of a pregnancy with twins, triplets, or more.

Age

According to the Office on Women’s HealthTrusted Source, women who are aged 30 years or older are more likely to conceive twins. The reason for this is that women of this age are more likely than younger women to release more than one egg during their reproductive cycle. If sperm fertilizes two separate eggs, a twin pregnancy can occur.

Height and weight

The ASRM report that nonidentical twins are slightly more common in taller or heavier women than they are in small women. The reasons for this are not clear, but it may be due to better nutrition. Women with a higher body weight may have more resources available for a developing fetus.

Racial background

In the U.S., Hispanic women are less likely to have twins than non-Hispanic white women or black women, according to the ASRM.

Increasing the chance of twins

Fertility treatments can increase the chance of having twins.

There are many unproven claims about how to increase the likelihood of conceiving twins. Some people advise following specific diets or using certain alternative therapies, but there is no scientific evidence to support these methods.

Fertility treatments, particularly IVF and ovary stimulants, do increase the chances of having twins. However, a twin pregnancy is riskier for both the woman and the developing fetuses. For this reason, some fertility clinics advise against implanting multiple embryos during IVF treatment.

The CDCTrusted Source recommend that younger women who are having their first fertility treatment select just one embryo for transfer to their womb.

As the success of fertility treatment is improving, there is often less need to transfer more than one embryo. In the U.S., the number of IVF treatments involving the transfer of three or four embryos decreased significantly between 2007 and 2016Trusted Source. Transferring just one or two embryos reduces the likelihood of a multiple pregnancy.

A twin pregnancy increases the risk of:

premature birth

low birth weight

stillbirth

disabilities at birth and congenital health conditions, such as cerebral palsy and autism

preeclampsia

diabetes during pregnancy

cesarean delivery

needing bed rest while pregnant

Summary

Although certain factors increase the chance of having twins, there is no way to improve the odds of having twins naturally. A woman will usually find out that she is pregnant with twins from an ultrasound early on in the pregnancy.

Some symptoms may indicate a twin pregnancy, including more intense morning sickness and very rapid weight gain. Regular medical appointments will improve the chances of a healthy pregnancy.