Does Obesity Cause Miscarriage?

Questions Remain In the Association Between Weight and Pregnancy Loss

pregnant woman ultrasound
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There has been a lot of research on the link between obesity and miscarriage, and it seems fairly clear that weight is a risk factor. Does obesity, though, actually cause miscarriage? That's certainly up for debate.

What's At Stake?

Body weight is a sensitive subject for most people. Very few women in the U.S. are satisfied with their bodies. Many women struggle with their weight for their entire lives, sometimes facing depression, anxiety and low self-esteem, because of the ceaseless internal and external pressure to lose weight.

Almost everyone who is overweight is well aware of the matter and does not need to be told about the health risks of being overweight.

In addition, many women are tempted to blame themselves for their miscarriages in the absence of a clear cause - so a link between obesity and miscarriage makes an already emotionally charged issue even more so.

Research on Obesity and Miscarriage

Obesity is statistically associated with an increased risk of pregnancy complications, ranging from miscarriage to problems later in pregnancy. Obesity also seems to increase the risk of recurrent miscarriages. Multiple studies have documented the link between obesity and the risk of miscarriage, and a few have even shown that losing weight seems to reduce the risk of miscarriage for patients who are overweight and have a history of miscarriage.

Doctors suspect that obesity is also responsible for the increased miscarriage rates in women with polycystic ovarian syndrome (PCOS).

Women with this disorder are more likely to be overweight, and women with PCOS who are able to lose weight also seem to reduce their own risk of miscarriage.

The American College of Obstetricians and Gynecologists, the professional U.S. organization for OB/GYNs, recommends that doctors offer nutritional counseling for obese women who are planning a pregnancy.

A Perspective On the Evidence

Even though the link between obesity and miscarriage seems to be real, it's important to remember that things aren't that open and shut. The majority of women who are overweight do not have miscarriages, so there must be other factors in play for those who do have miscarriages. In addition, obese women who have one miscarriage usually have successful subsequent pregnancies. Unfortunately, doctors do not yet have all the answers in this area of research.

It's also a gross oversimplification to say that a miscarriage is an obese woman's fault because she ate too much and didn't exercise. Very few people are obese by choice, and a person's weight often involves a complex interworking of physiological and psychological factors that must be overcome to lose weight. It's also very likely that there's genetic involvement in obesity.

It's possible that the complex factors that cause some women to be overweight also cause miscarriage in some of these women. It's also possible that losing weight reduces the impact of those pre-existing factors on the subsequent pregnancy.

Right now we simply do not know.

Your Weight and Pregnancy

It does seem that losing weight can reduce one's risk of miscarriage, whether that's due to losing the weight itself or some other reason. If you wish to lose weight, try to do so safely under the guidance of a doctor or nutritionist. It's better to approach a healthier lifestyle as the goal rather than a specific number of pounds or clothing size.

It's not fair that some of us have to struggle harder than others to have a healthy body weight. And rarely is the process as simple as choosing to eat less and exercise more. Consider finding a support group to help you throughout the process. You can also visit our calorie counter to help get on your way.

Finally, if you are overweight and have suffered a miscarriage, resist the temptation to assume that your weight was the cause. You should not blame yourself for the miscarriage(s) you may have had. No one can say with certainty what caused a past miscarriage without laboratory testing, and obesity is not something that can be proven as a cause of any specific miscarriage.

Remember that whether you lose weight or not, your odds of having a successful next pregnancy are higher than your odds of having another miscarriage.

In addition, if you are currently pregnant and feel you are overweight, talk to your doctor with any concerns about your diet and exercise, although pregnancy is generally not the best time to implement a weight-loss plan.

Sources:

ACOG Issues Guidance to Ob-Gyns on Impact of Obesity During Pregnancy. American College of Obstetricians and Gynecologists. August 31, 2005. 

Clark, A.M., Thornley, B.,  Tomlinson, L., et al. (1998). Weight loss in obese infertile women results in improvement in reproductive outcome for all forms of fertility treatment. Human Reproduction. 

Lashen, H., Fear, K. and Sturdee, D.W. (2004). Obesity is associated with increased risk of first trimester and recurrent miscarriage: matched case–control study. Human Reproduction.

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