Chances of Having Twins Calculator

Created by Dominika Miszewska, MD, PhD candidate
Reviewed by Dominik Czernia, PhD candidate and Jack Bowater
Last updated: Nov 22, 2021

Double the trouble, double the fun, double the love! (Or maybe triple?) With our chances of having twins calculator, you can calculate what are the chances of having twins, triplets, or any other multiple pregnancy.

Multiple pregnancies are now a hot topic, as ARTs (Assisted Reproductive Technology), such as in vitro fertilization, are making women more fertile and susceptible to twins. As more and more women give birth to more than just one baby, you may ask "Why is that a thing?", "What are my chances of having twins?", and "How to have twins?" Answers to these questions, and more, can be found in the article below.

Types of multiple pregnancies - how do they happen?

Multiple pregnancies aren't a common thing. One could say that this is natural - pregnancy is burdensome on the mother's body, as she has to feed the fetus, and give it space to grow and develop until he or she is ready to be born. In the cases of multiple pregnancies, things become more complicated. To keep both the babies and the mother safe, birth often has to be induced before the due date to keep everyone safe.

What are the types of multiple pregnancies?

  • Monozygotic twins, where a single egg cell is fertilized by a single sperm cell. Later, it splits into two, instead of growing into just one embryo. The children have the exact same genetic material, and are always of the same sex. They also look identical.
  • Dizygotic twins, where two egg cells are released during one ovulation, and then fertilized by two sperm cells. Our calculator is mostly concerned with this type of pregnancy, as it is more common and more influenced by external factors. The children look different, as their DNA is also different. They may be of two different sexes - akin to regular brothers and sisters.
  • Triplets, quadruplets, etc. - the more babies that were conceived, the more eggs that were fertilized by sperm cells. These types are increasingly less likely to happen naturally - 1 in 10,000 for triplets and 1 in 70,000 for quadruplets.

What are the chances of having twins, triplets, or quadruplets with natural methods?
For monozygotic twins, they equal 0.3%. In the case of dizygotic twins, the odds go up to 0.4%. If you think of triplets, the natural probability is 0.01%, and for quadruplets, it's only 0.00014286%.

Factors that influence your having twins odds

There are several factors which either increase or decrease your chances of having dizygotic twins. Among them, a surprising one is an ethnicity, as Hispanic couples are the least prone to having twins. Then there are White parents. The highest chances of multiple pregnancies have Afro-Americans.

The most significant factor which affected the number of twin pregnancies and increased it substantially in the last years is ART treatment. Not only the in-vitro fertilization itself but also hormonal therapy.

How to have twins with natural methods? Now we've come to the genetic issues. Most people know that having twins in their family gives them some hope for conceiving twins again. Twins on the mother's side are more influential than on the father's.

What are my chances of having twins, if I've already had one pair? The odds of having younger ones again are high - up to 1 in every 17 pregnancies!

What became very clear after the war and every period of famishing in societies, is that the higher and stronger the mother is, the higher are the odds of having twins. What might be the reason? Scientists suggest that bigger moms have more nutrients stored, and therefore, the babies' development is not that interrupted, even if they're two or more.

Women suffering from obesity (BMI over 30) are more likely to get pregnant with twins. Probably it's due to the hormonal disintegration. Excessive adipose tissue produces estrogens. This hormone initiates maturation of eggs and ovulation. If there's too much of it, more than one egg (which is the typical number) matures and moves towards the fallopian tubes. And so, the sperm cells can fertilize more than just one egg.

How to calculate my chances of having twins? - Changes of having twins calculator

In the first box, you can choose what type of multiple pregnancies you want to calculate the odds. The following result is the chances of natural conception of multiple pregnancies.

The rest of the calculator is designed for dizygotic twins calculations. First, check with your ethnicity, what are the overall odds, for the general population of chosen ethnicity.

The next six questions focus mainly on known factors that increase the couple's chances of conceiving twins. Choose your factors; you can also play with the tool and get to know which factors principally increase the odds. Note that the numbers don't add up. Of course, having more than one factor, which affects the result, increases it a bit more.

How to have twins? What can I do?

OK, so now I know how to calculate my chances of having twins. But how do I get pregnant with ones? If your dream is having twins or triplets, there's unfortunately not so much you can do. Most of the factors affecting the probability are genetic or connected with your body weight. And risking obesity for the sake of increased chances for twins is not the best option. You can always talk with your physician about ART. That includes pharmacotherapy or in-vitro fertilization, putting your hormonal regulations at risk again.

Dominika Miszewska, MD, PhD candidate
Overall chances of having a multiple pregnancy
Type of pregnancy
Dizygotic twins 👧👦
Naturally, dizygotic twins occur only in 1:85 pregnancies.
What increases the chances of having dizygotic twins?
Your ethnicity
Did you get pregnant with the help of ART? 💉
Do you have nonidentical twins in your family?
Have you already have twins? 👧👦
Does the mom-to-be have a twin brother/sister?
What's the mom-to-be's height?
What's the mom-to-be's weight? ⚖️
✔️ White couples have a medium chance of having twins when compared with other ethnicities - almost 3.5 in 100 pregnancies.
You are not at an increased chance of conceiving twins.
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