7 Factors That Increase the Chances of Having Twins

Although they're not completely infallible factors, there are several situations that increase the chances of having twins. Here, we'll explain them in detail.
7 Factors That Increase the Chances of Having Twins

Last update: 03 February, 2022

The chances of having twins by natural conception are quite low. Through assisted reproductive techniques, it’s much more likely.

Fraternal twins and identical twins, are they the same?

Although the terms “twin” refers to both fraternal and identical pairs, there’s a very important difference between the two. Fraternal twins are formed in different eggs, which are fertilized by two separate sperm.

In the case of identical twins, the same egg is fertilized once by one sperm and then divides into two. Identical twin pregnancies aren’t very typical. The genetic information in the case of twins is identical.

Factors that make it more likely to have twins

A black and white photo of newborn twins snuggling while they sleep.

One in 90 pregnancies that occur by natural conception leads to twins. However, not all women are equally likely to be mothers of twins. Studies have determined the incidence of certain factors, such as:

1. A woman’s age

A woman’s fertility decreases as she gets older. However, her hormonal load increases. Therefore, while a woman is younger, she has only a 4% chance of having more than one child. Whereas, after the age of 45, the chances are close to 70%.

2. Genetic inheritance

A family whose women have had twins will certainly pass this trait onto their daughters. Studies have shown that the birth of twins is due to a maternal genetic relationship. That is, even if there are twins in a man’s family, he won’t have them because of this.

However, a man can pass on the tendency to his female daughters. He may not be able to procreate twins, but his daughters will have the possibility.

3. Good nutrition

Certain opinions point out that in times when populations have been affected by war and food shortages, multiple pregnancies are sharply reduced. However, a country like Nigeria, with overpopulation and the typical problems of access to a varied diet that occur as a result, has the highest rate of twins in the world.

4. Height and body weight

Tall women with a height greater than 5 feet, 4 inches are statistically more likely to have twins. At the same time, the higher the body mass index, the greater the chances of having twins. According to studies by the American Academy of Obstetrics and Gynecology, women with a high body mass tendency over 30 are more likely to have twins.

BMI is calculated by dividing body weight expressed in kilograms by the square of height in meters. This type of measurement is also associated with other characteristics.

Twin baby girls wearing coordinating outfits and smiling at eachother.

However, studies claim that obesity has a detrimental impact on fertility. Obese women are three times more likely to have reduced fertility than non-obese women, “both in natural cycles of spontaneous ovulation and in cycles of induced ovulation in assisted reproduction”.

Indeed, excess weight generates endocrine and metabolic abnormalities that can affect ovarian and reproductive function.

5. Ethnic group

The women most prone to twin pregnancies are black African women, in particular, as already noted, those from Nigeria. This is followed by white Caucasian women. Asian women have the lowest rate.

6. History of twin pregnancies

There is no greater predictor of a woman’s chances of having twins than having had a previous pregnancy with these characteristics. If a woman has had twins in previous pregnancies, she may become pregnant with twins again in the future. This is especially possible when there’s been no intervention. That is, when the pregnancy has resulted naturally, the tendency to ovulate is considered multiple.

It’s understood that when a woman doesn’t need to be stimulated to have more than one baby per pregnancy, she has a greater predisposition. Consequently, she’s a perfect candidate to relive this experience.

7. Fertility and in vitro fertilization

Treatments to improve fertility by including drugs that stimulate assisted reproductive techniques and the transfer to the uterus of several embryos (in the procedures in vitro procedures), have increased the number of multiple pregnancies and consequently the care of preterm babies.

Twin pregnancies have increased because women have delayed childbearing and, consequently, assisted pregnancies have increased. However, this has meant an increase in complications and risks to maternal and fetal health, which must be adequately and timely addressed medically and/or surgically.

All cited sources were thoroughly reviewed by our team to ensure their quality, reliability, currency, and validity. The bibliography of this article was considered reliable and of academic or scientific accuracy.

  • McLennan AS, Gyamfi-Bannerman C, Ananth CV, Wright JD, Siddiq Z, D’Alton ME, Friedman AM. The role of maternal age in twin pregnancy outcomes. Am J Obstet Gynecol. 2017 Jul;217(1):80.e1-80.e8. doi: 10.1016/j.ajog.2017.03.002. Epub 2017 Mar 9. PMID: 28286050; PMCID: PMC5571734.
  • The University of Western Australia. Older women more likely to conceive twins. Disponible en: https://www.uwa.edu.au/news/Article/2020/May/Older-women-more-likely-to-conceive-twins.
  • MedlinePlus. ¿Está determinada por la genética la probabilidad de tener gemelos? Disponible en: https://medlineplus.gov/spanish/genetica/entender/rasgos/gemelos/.
  • Akinboro A, Azeez MA, Bakare AA. Frequency of twinning in southwest Nigeria. Indian J Hum Genet. 2008 May;14(2):41-7. doi: 10.4103/0971-6866.44104. PMID: 20300293; PMCID: PMC2840794.
  • Signore C, Mills JL, Cox C, Trumble AC. Effects of folic acid fortification on twin gestation rates. Obstet Gynecol. 2005 Apr;105(4):757-62. doi: 10.1097/01.AOG.0000154886.40318.5e. PMID: 15802402.
    de la Calle M, Bartha JL, Marín C, Rus JC, Córcoles G, Ruvira S, Ramiro-Cortijo D.
  • Maternal Obesity in Twin Pregnancy: The Role of Nutrition to Reduce Maternal and Fetal Complications. Nutrients. 2022 Mar 22;14(7):1326. doi: 10.3390/nu14071326. PMID: 35405938; PMCID: PMC9003274.
  • Barrios-De-Tomasi J, et al. Efecto de la obesidad en la reproducción femenina. Rev Mex Cienc Farm 2013;44(3):8-18. Disponible en: https://www.scielo.org.mx/pdf/rmcf/v44n3/v44n3a2.pdf.
  • Vallejo Ardila Dora Lucía, Rangel Díaz Yully Andrea, Angarita Fonseca Adriana, Cardona Eliana Patricia. Estado actual del embarazo gemelar: Revisión de la literatura. Rev. Univ. Ind. Santander. Salud [Internet]. 2012 Dec [cited 2023 Feb 12] ; 44( 3 ): 41-48. Available from: http://www.scielo.org.co/scielo.php?script=sci_arttext&pid=S0121-08072012000300006&lng=en.

This text is provided for informational purposes only and does not replace consultation with a professional. If in doubt, consult your specialist.