Can being overweight make it harder to get pregnant?

From organic food to stress to sleep patterns, everyone has an opinion on what you should change to give you the best chance for conception and a healthy pregnancy. We may not have even identified all the different parts of our lives that could have an affect on our fertility, but experts agree on a few of these variables, and being overweight is one them. The risks are scary. Not only because they can make conception more difficult, but also because excess fat can be harmful to the mother and baby. Much like giving up smoking and alcohol, changing diet and exercise behavior is not easy (did you know sugar is found to be as addictive as drugs?!) (DiNicolantonia 2017). That said, just as it is possible to give up smoking, drinking too much, and/or drugs, it is possible to lose weight.


Education is power, and understanding the science behind why being overweight is harmful and how to lose weight for the long term, may foster the motivation to make the necessary lifestyle changes worth the benefit of being healthy. The good news is that if you are carrying around a couple of extra pounds, you may not have to lose as much as you think to make a major impact on your health and fertility.

Am I overweight?

You may already know that being overweight leads to multiple health problems such as diabetes and cardiovascular disease, but not everyone is aware that excess fat can also lead to infertility. In obesity, the fat cells produce hormones that can lead to disrupting multiple pathways in the body, leading to insulin resistance, inflammation, hypertension, cardiovascular risk, hypercoagulation (excessive blood clotting), and oocyte (egg) development problems (Pi-Sunyer 2009).

Knowing two numbers may help you understand your risk: your body mass index (BMI) score  and your waist size in inches (Noble 2001).

BMI

  • normal weight: BMI of 18.5 to 24.9
  • overweight: BMI of 25 to 29.9
  • obesity: BMI of 30 or higher


(National Institute of Diabetes and Digestive and Kidney Diseases)

Trying to Get Pregnant

Being overweight or obese can increase the risk of experiencing irregular periods, infertility, and miscarriage. While none of these are guaranteed to happen to a woman who is overweight or obese -- and these risks can also happen to a woman who is not overweight -- the more overweight you are, the more at risk you are for these complications (Pi-Sunyer 2009).

An increase of unwanted fat may actually cause changes in hormone function that could lead to irregular cycles and sometimes even amenorrhoea (no period), which is the result of an increase in certain sex hormones. Amenorrhoea indicates that ovulation is likely not occurring, which makes conception difficult (Ogunbode 2009).

PCOS

One of the most common hormonal complications in women of reproductive age is a condition called polycystic ovarian syndrome (PCOS). PCOS is significantly correlated with being overweight or obese (Sam 2007); either being overweight can lead to PCOS or PCOS can lead to being overweight. Regardless of the reason behind how a woman has PCOS, what we do know is that it can cause infertility.

Women with PCOS produce excess androgens, a male hormone, which may lead to irregular cycles and difficulty with getting pregnant (Wu 2014). In addition, a significant link between PCOS and insulin production exists; women with PCOS either produce too much insulin or the insulin they product does not work effectively. Insulin malfunction is one of the reasons for having a hard time losing weight (Obesity Action Coalition).  Recent research supports evidence that a low-carb diet and exercise does help women with PCOS lose weight and improve hormone levels (Sweatt K 2015).

Miscarriage

Miscarriage is also a high risk in obese women. This is found to be due, in part, to poor oocyte (egg) quality. Research shows that oocytes in obese women do not mature as they do in healthy women (Davis 2016).

Type 2 Diabetes and Fertility

Being overweight or obese significantly increases risk for Type 2 diabetes. More than 90 percent of people with type 2 diabetes are overweight or affected by a degree of obesity (Obesity Action Coalition). Diabetes may make getting pregnant difficult, but stuides show that when women with Type 2 diabetes had better glycemic control, they were able to increase their fertility rates nearly to the same as the general population (Livshits 2009). Good glycemic control is essential before getting pregnant to prevent congenital malformations and miscarriages in young women with Type 2 diabetes (Szaboova 2015).

Researchers still don’t really know the answer to why excess fat is dangerous or can cause certain diseases. When it comes to diabetes, the current speculation is that fat may cause the cells to change. This change makes them resistant to insulin, making it more difficult for the body to carry sugar from the blood to the cells (National Institute of Diabetes and Digestive and Kidney Diseases). This, in turn, results in high blood sugar, and over time, the cells gradually fail from fatigue.

Pregnancy

Obesity may affect the mother by increasing the risk for conditions or issues like gestational diabetes, preeclampsia (high blood pressure), sleep apnea, and issues with diagnostic tests (ACOG). In addition to being dangerous for mom, the baby and pregnancy are also at higher risk for miscarriage, birth defects, macrosomia (when the baby is larger than normal), preterm birth, stillbirth, and cesarean delivery  (ACOG). Babies of overweight or obese mothers are also at an increased risk of being born too soon, being stillborn (dead in the womb after 20 weeks of pregnancy), and having neural tube defects (defects of the brain and spinal cord) (National Institute of Diabetes and Digestive and Kidney Diseases).

Preeclampsia

Preeclampsia is high blood pressure during pregnancy that can cause severe problems for both mother and baby if left untreated. There is compelling evidence that obesity increases the risk of preeclampsia about 3-fold (Roberts 2012).

Gestational Diabetes

Gestational diabetes mellitus (GDM) is a type of diabetes that occurs during pregnancy.  It causes high blood sugar that can harm both the mother and the baby’s health. Eating healthy foods and exercising can help control GDM and help prevent a difficult birth (Mayo Clinic 2017). The risks of GDM include excessive birth weight and preterm labor (babies born early may experience respiratory distress syndrome).GDM could also cause the baby to be born with low blood sugar that, if severe, may provoke seizures and Type 2 diabetes. Additionally, babies of mothers who have GDM are more at risk for developing obesity and Type 2 diabetes later in life (Mayo Clinic 2017).

Even though GDM typically resolves soon after delivery (CDC), women with a history of GDM remain at increased risk of developing Type 2 diabetes mellitus in the future (Kim 2010).

Increased need for C-section Labor

Being overweight also increases the risks associated with surgery and anesthesia, and severe obesity increases surgery time and blood loss. Gaining too much weight during pregnancy can have long-term effects for both mother and child. One possible consequence is  that the mother will be overweight or obese after the child is born. Another risk is that the baby may gain too much weight later as a child or an adult. If you are pregnant, talk to your health care provider about how much weight gain is right for you during pregnancy (National Institute of Diabetes and Digestive and Kidney Diseases).

Summary

The good news is that if you are overweight or obese and are trying to conceive, losing just 5-7% of your body weight may improve overall health and “pave the way for a healthier pregnancy” (ACOG). 

In summary, for women that are overweight or obese, losing 5-10% of their body fat can improve fertility, reduce the risk for pregnancy complications, as well as reduce complications for the babies health. While the diet fads may make it seem like it: there is no secret to losing weight. Losing weight requires a diet overhaul for most of us living in the United States. It means significantly reducing sugar, refined carbohydrate intake and processed foods. It also means exercising daily. 

One 'trick' for starting new healthy habits is not to think of deprieving oneself, or saying 'no' to unhealthy food, but to think of giving to oneself and saying 'yes' to the gift of health.




References:

  1. https://bjsm.bmj.com/content/52/14/910
  2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2879283/
  3. https://www.nhlbi.nih.gov/health/educational/lose_wt/BMI/bmicalc.htm
  4. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1071369/
  5. https://www.niddk.nih.gov/health-information/weight-management/health-risks-overweight
  6. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2879283/
  7. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4111009/
  8. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4111009/
  9. https://www.obesityaction.org/community/article-library/polycystic-ovarian-syndrome-pcos-and-obesity/
  10. ‍https://www.fasebj.org/doi/abs/10.1096/fasebj.29.1_supplement.596.12
  11. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2879283/
  12. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4111009/
  13. https://www.obesityaction.org/get-educated/public-resources/brochures-guides/understanding-excess-weight-and-its-role-in-type-2-diabetes-brochure/.
  14. https://www.ncbi.nlm.nih.gov/pubmed/19863473
  15. https://www.niddk.nih.gov/health-information/weight-management/health-risks-overweight
  16. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4494467/
  17. https://www.acog.org/Patients/FAQs/Obesity-and-Pregnancy?IsMobileSet=false
  18. https://youngwomenshealth.org/2013/12/12/pcos-nutrition/
  19. https://www.whattoexpect.com/getting-pregnant/health-and-wellness/safeguard-your-health/exercise-before-pregnancy.aspx.
  20. https://www.mayoclinic.org/healthy-lifestyle/getting-pregnant/expert-answers/weight-loss-before-pregnancy/faq-20380882.
  21. https://priyaring.com/blog/safe-workout-plans-for-women-trying-to-conceive/exercise/fertility
  22. https://priyaring.com/blog/can-exercise-help-with-fertility/trying-to-get-pregnant.
  23. https://www.acog.org/Patients/FAQs/Obesity-and-Pregnancy?IsMobileSet=false

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