Does high weight in pregnant women increase the risk of miscarriage?

By (embryologist) and (psychologist).
Last Update: 01/27/2022

Obesity in pregnant women is associated with an increased risk of certain obstetric complications such as gestational diabetes or preeclampsia. However, elevated body mass index (BMI) in pregnant women has also been linked to the risk of miscarriage.

Although the causes of obesity leading to this increased miscarriage rate are unclear, the uterine inflammatory environment may be related.

Obesity and female fertility

Obesity has been linked to infertility in women, as the associated hormonal alterations can cause problems for ovulation to occur correctly and menstrual imbalances.

However, the reproductive potential of these women would be reduced even with normal menstrual cycles. This means that obesity would lead to a longer time to pregnancy, but not only because of the ovulatory problems mentioned above.

Therefore, the oocytes, embryos, and/or endometrium could also be affected if the woman suffers from obesity.

On the other hand, the results of assisted reproduction techniques are also worse in the case of obese patients, with a lower live birth rate.

Obesity and pregnancy

Once pregnancy is achieved, if the woman has a high BMI, she may present a greater number of complications. Among them, we can mention the following:

  • Gestational diabetes
  • Preeclampsia and hypertension problems
  • Spontaneous abortion
  • Premature delivery

Additionally, the risk of cesarean delivery would also be increased in these patients.

Effects on offspring

Notwithstanding the above, obesity in pregnant women can also have effects on their offspring. Children born to a woman with a high BMI may be more likely to suffer:

  • Obesity
  • Diabetes
  • Hypertension

On the other hand, maternal obesity may increase the risk of certain congenital anomalies and of having a larger or high birth weight baby(macrosomia).

Obesity and abortion

As we have mentioned, overweight and obesity are associated with an increased risk of miscarriage, whether pregnancy has been achieved naturally or with the help of assisted reproductive techniques.

In addition, obesity seems to increase the risk of miscarriage independently of whether the woman has polycystic ovarian syndrome(PCOS) or not.


The causes for obesity to influence this increased risk of miscarriage have not been clarified. It has been proposed that obesity would lead to an affectation of the oocytes and, therefore, of the embryo. However, the involvement of the uterine environment could also play an important role.

Women with obesity problems have been found to have a higher rate of miscarriage after the transfer of euploid embryos (with the correct number of chromosomes).

This suggests that embryonic aneuploidy is not the factor responsible for the increased risk of miscarriage in obese patients.

Therefore, all this leads to think of a possible uterine or placental alteration that leads to the interruption of embryonic development.

Repeated miscarriage

Repeat miscarriage, although there has been some controversy in its definition, is the loss of two or more previous pregnancies.

Although there are certain known causes for this condition, obesity may also be related to recurrent miscarriage. For women with a history of repeat miscarriage, a BMI greater than 30 increases the risk of miscarriage for a future pregnancy.

Because obesity is associated with chronic inflammation, the immune system may be involved in the increased number of obstetric complications in these patients.

Risk reduction

Due to all the obstetric complications, we have mentioned that can occur when a woman becomes pregnant with obesity, one of the main measures to adopt would be to lose weight before seeking gestation.

A Mediterranean diet based on vegetables, fruits, cereals, legumes, and fish could help to keep weight under control, as well as be associated with low levels of inflammation.

On the other hand, it is equally important to control weight gain during pregnancy so that it is not excessive. However, losing weight or gaining too little is also not ideal during pregnancy.

Finally, it should be noted that if the woman has high postpartum weight retention, it may increase the risk of obstetric complications in the next pregnancy.

FAQs from users

Is there any benefit or advantage to being overweight to avoid abortion?

By Silvia Azaña Gutiérrez B.Sc., M.Sc. (embryologist).

No, an elevated body mass index (BMI) in pregnant women is not beneficial, as it is associated with certain obstetric complications. These include an increased risk of miscarriage.

What are the risks of obesity in pregnancy?

By Silvia Azaña Gutiérrez B.Sc., M.Sc. (embryologist).

A woman who becomes pregnant with obesity has an increased risk of complications during pregnancy, for herself and for the baby.

If the woman has a high BMI, the risk of gestational diabetes, preeclampsia, hypertension and miscarriage is increased. In addition, the risk of cesarean delivery is also increased.

For the offspring, maternal obesity can lead to an increased risk of obesity, hypertension and diabetes, as well as certain congenital anomalies.

If you are interested in knowing more about recurrent miscarriage, we recommend you to visit the following link: What is recurrent miscarriage - Causes, diagnosis, and treatment.

On the other hand, if you want to read more in-depth about the different types of miscarriage, you can visit this article: Types of miscarriage: how many are there and how do they differ?

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FAQs from users: 'Is there any benefit or advantage to being overweight to avoid abortion?' and 'What are the risks of obesity in pregnancy?'.

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 Silvia Azaña Gutiérrez
Silvia Azaña Gutiérrez
B.Sc., M.Sc.
Graduate in Health Biology from the University of Alcalá and specialized in Clinical Genetics from the same university. Master in Assisted Reproduction by the University of Valencia in collaboration with IVI clinics. More information about Silvia Azaña Gutiérrez
License: 3435-CV
Adapted into english by:
 Cristina  Algarra Goosman
Cristina Algarra Goosman
B.Sc., M.Sc.
Graduated in Psychology by the University of Valencia (UV) and specialized in Clinical Psychology by the European University Center and specific training in Infertility: Legal, Medical and Psychosocial Aspects by University of Valencia (UV) and ADEIT.
More information about Cristina Algarra Goosman
Member number: CV16874

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