Overview
Do you wish for twice the newborn cuteness but believe it’s out of the question? In reality, having twins may not be such a crazy idea. (Remember, it’s also twice as many diaper changes.)
Twin births increased by 72 percent between 1980 and 2018, Trusted Source. In 2018, there were approximately 33 sets of twins born per 1,000 births in the United States.
But, before you go out and buy matching outfits and names, it’s important to understand how twins are conceived and the additional factors that come into play. Some circumstances, whether natural or acquired through fertility treatments, may increase your chances of having twins.
Naturally having twins
It is estimated that one in every 250 pregnancies results in twins, and there are two ways to get them.
Identical twins
The first is the fertilization of a single egg by a single sperm. Reproduction 101, right? The fertilized egg, however, divides into two along the way, resulting in identical twins.
The likelihood of having identical twins is low about 3 or 4 in every 1,000 births. While it may seem obvious, identical twins are always the same sex at birth, either both boys or both girls. Why? They not only look alike, but they also have the same DNA.
Fraternal twins
Fraternal twins, on the other hand, are produced when two distinct eggs are fertilized by two distinct sperm cells. Both fertilized eggs implant in the uterus and two babies are born 9 months later.
Fraternal twins maybe two boys, two girls, or one boy and one girl. They may or may not resemble each other. This is because, unlike identical twins, they do not share the same DNA. Aside from age, they’re no more alike than siblings born years apart.
Factors that increase your chances of naturally having twins
Genetics
You’ve probably heard that twins “run in families.” This is only partially correct. If you are a fraternal twin or if fraternal twins run in your family, your chances of having fraternal twins are higher. One reason for this could be hyperovulation, a condition in which the body produces two or more eggs during ovulation — essentially a requirement for having fraternal twins.
And, interestingly, hyperovulation can be passed down through your DNA from your mother’s or father’s genes. (It can also happen in women who don’t regularly release more than one egg or have twins in their family on occasion.)
Age
Are you over the age of 35? If you want to have twins, you might be in luck if you’re also in your upper 30s or 40s. According to the Mayo Clinic, women of “advanced maternal age” (we apologize for using the phrase, but it’s commonly used in medical settings to mean over the age of 35) have a higher chance of conceiving twins.
Hormonal changes as you approach menopause may cause your body to release more than one egg during ovulation. If two or more are fertilized and both implant, your nursery may only require two cribs.
Height
Twins appear to be more common in taller women. This may sound strange, but researchers attribute this possibility to an insulin-like growth factor.
According to a 2006 study trusted Source that looked at the heights of 129 women who had “spontaneous multiples,” their average height was nearly 5 foot 5 inches, while the national average for all women at the time was 5 foot 3 3/4 inches.
Weight
Women who are overweight or obese have a higher chance of naturally conceiving twins. According to a 2005 study trusted Source that examined data from over 51,000 births in the United States, the chances are greatest if your body mass index (BMI) is greater than 30.
According to a later study from 2016 that examined maternal characteristics in Norwegian women, twin pregnancies were more common in women with BMIs over 25.
Here’s a word of caution: Don’t eat more to increase your chance of having twins. Talk to your doctor about a healthy weight for you before becoming pregnant because having a BMI over 30 may also put you in the high-risk category for pregnancy.
Race
According to birth statistics from 2018 in the United States, black women give birth to twins more frequently than white women do. But compared to the other groups, Asian and Hispanic women deliver twins at a lower rate.
Diet
A previous study by Trusted Source (by the same researcher who reported in 2006 on the maternal height factor potentially affecting twin births) discovered that vegans (those who do not consume dairy products) have one-fifth the rate of twin births as women who do consume dairy.
This could happen because women who eat dairy may consume more insulin growth factors. This hormone is released by cows into their milk, and when consumed, it may affect human reproduction. It should be noted that this is only one analysis of the medical records of those who had given birth. Since then, little (if any) research on the effect of dairy consumption on the twin birth rate has been completed.
A 2008 evaluation According to Trusted Source, the Yoruba people of southwest Nigeria, which has the highest rate of twin births in the world, may be more likely to experience twin pregnancies if they eat yams. Yams are thought to “contain a natural hormone phytoestrogen, which may stimulate multiple ovulation,” according to popular belief.
Although increasing your consumption of this root vegetable is not a surefire way to conceive multiples, yams are a healthy food that is packed with fiber, vitamins, and minerals.
Pregnancies in the past
Do you already have a child who is interested in becoming a big brother or sister? He or she could be the reason you have twins. That’s correct! A previous pregnancy, or even multiple pregnancies, may increase your chances of having twins.
According to, women between the ages of 35 and 40 who have four or more children are three times more likely to have twins than women under the age of 20 who do not have children.
Having twins while undergoing fertility treatments
If you’re familiar with artificial reproductive technology (ART), in vitro fertilization (IVF), and other fertility treatments, such as intrauterine insemination (IUI), you’re probably aware that twins are a possibility.
IUI
While IUI does not increase your chances of having twins, certain drugs used in conjunction with it may. Ovulation-stimulating medications include clomiphene citrate (Clomid) and letrozole (Femara).
Both of these medications are frequently used in IUI cycles and may assist the body in producing multiple eggs that may release at the same time. Twins are possible if two (or more) eggs are fertilized and implanted.
The rate of twins with Clomid was 7.4 percent in one 2014 study. Femara had a rate of only 3.4 percent. Those figures may not appear to be high, but they are significantly higher than the chance of naturally conceiving twins.
There’s even more. Gonadotropins, like follicle-stimulating hormone (FSH), stimulate egg follicle growth. These injectable medications are also commonly used in IUI and other fertility treatments, and the rate of twins while using them is a whopping 30%.
IVF
IVF also includes drugs. However, the number of embryos transferred is one of the main factors that increase your chances of having twins with this reproductive technology. Some couples prefer to transfer only one. While the single embryo could split and produce identical twins, this is unlikely.
The more likely scenario involves fraternal twins. Twins (or more!) are on the way if you transfer two (or more) embryos and they both successfully implant and develop.
Twin pregnancies with IVF using fresh embryos occur at a rate of 12.1 percent Trusted sources for women under the age of 35 and 9.1 percent for trusted sources for women aged 35 to 37. The chances of having twins decrease with age (unlike natural twin conception), with women aged 38 to 40 having a 5.3 percent Trusted Source rate. And the rate for those aged 43 and up is only 0.5 percent of trusted sources.
Consider the following: During IVF, some couples may choose to transfer two embryos. Assume one of those embryos divides and all three implant in the uterus. The result would be triplets -two identical twins and one fraternal sibling.
How to Improve Your Chances
Before you start pinning cute twin nurseries to your Pinterest board, keep in mind that twin pregnancies aren’t always fun and (baby shower) games.
Being pregnant with multiples may result in complications, and you will be classified as “high risk” by your doctor or midwife. Women who are pregnant with twins are more likely to develop preeclampsia and gestational diabetes. That is not to say that a healthy pregnancy with two children is impossible. It simply means you may need to be monitored more closely.
Aside from the risks, many of the factors that increase your chances of having twins are beyond your control.
You can choose to eat more dairy and yams, but you can’t change your height, race, or family history of multiple births. Gaining weight on purpose before pregnancy is also not always a good idea. And, if you plan on having children later in life to increase your chances of having twins, keep in mind that with age comes decreased fertility and an increased risk of chromosomal abnormalities.
If you insist on having two children, reproductive technology may give you the most control. However, for the best results, experts currently recommend that younger women transfer only one embryo Trusted Source per IVF cycle.
Ovulation-inducing drugs, whether used alone or in conjunction with IUI, require a prescription and may carry serious risks, such as an increased risk of ovarian hyperstimulation or ectopic pregnancy.
Drugs and procedures such as IVF are also expensive and are usually reserved for couples who have been diagnosed with infertility. Infertility is defined as not becoming pregnant with timed intercourse within a year for women under the age of 35. This timeframe is reduced to 6 months for women over the age of 35.
We’re not attempting to be Debbie Downers. Discuss twins with your doctor, particularly your reproductive endocrinologist if you’re undergoing fertility treatments. They can tell you about any risks that are unique to you and whether doing a multiple-embryo transfer with IVF is an option.
Summary
Unfortunately, there is no magic pill that will guarantee you will be rolling a double stroller around your neighborhood like a boss. (However, we believe you’re a boss regardless.)
This isn’t to say you can’t have some fun trying to improve your chances by eating more cheese and roasted yams or crossing your fingers for your next IUI. There are risks and benefits to having twins. But, before you start daydreaming, try looking forward to seeing double… with the lines on your pregnancy test. We’re sending baby powder!
