While on the fertility journey, many women wonder about the possible impact of a variety of health and lifestyle factors. Far and away, weight – and the dietary and exercise choices to which it’s linked – is one of the most common concerns. As a very simple explanation, we often explain to patients that our brains and bodies still think we live in the prehistoric era, and a healthy weight is a mental tip that all is well, and it might be a good time to conceive.
THE SCIENCE OF WEIGHT & FERTILITY
The female reproductive system takes its cues from the adrenal system, a parallel axis of metabolism, nutrition and energy. In its most extreme forms, during the severe bouts of stress and malnutrition encountered in war or famine, the brain determines that in the absence of reliable incoming nutrition, energy should not be expended on reproduction. Women stop having their period (retaining their blood and iron stores) and stop ovulating (preventing conception). With less severe alterations in overall energy stores, the effect is not necessarily as profound, but even a 5-10% change in body weight can impact menstruation and fertility.
THE IDEAL WEIGHT FOR CONCEPTION
There are a few key points to take away when we think about weight and fertility. First, the right weight (not too low, not too high) gives the highest chance of a regular ovulatory menstrual cycle. You can use a normal body mass index or BMI (calculate yours here) as a rough guide.
But it’s not a perfect tool. Weight distribution (body types or shapes) can also influence our health. The apple body shape (abdominal fat) is most associated with health outcomes such as pre-diabetes, type 2 diabetes and so forth. Being on either side of what your body considers “normal” can result in an abnormal or absent period. Though we can certainly induce ovulation with medication, at least moving the weight in the right direction is always advisable.
Typically, we love to see a BMI close to the optimal range of 18.5-24.9 kg/m2, the risks certainly start to go up even more if the BMI gets well beyond this range, into the Class III obesity range of above 40 kg/m2. Being under- or overweight can interfere with ovulation and increase the miscarriage rate, while extra fat tissue can negatively affect egg quality, causing poorer embryo development, and the endometrium, or lining of the uterus, where implantation occurs.
UNEXPLAINED INFERTILITY & DIET
There are studies to indicate that, when compared to fertile women, patients with unexplained infertility showed significant abnormalities in dietary habits. These differences range from a minimal imbalance in micronutrients, which is often easily corrected with dietary supplementation, to the severe macro- and micronutrient deficiencies commonly seen with obesity. The latter could require long-term nutrition counseling and lifestyle modification to achieve health benefits. The Academy of Nutrition & Dietetics holds the position that all women of reproductive age should receive education about the maternal and fetal risks of obesity, excessive weight gain during pregnancy, and post-partum weight retention (50% of women don’t lose their “baby weight”).
We often recommend a dietician visit to help evaluate where you can make improvements, and almost all women could benefit from taking advantage of this opportunity. Similarly, there is also data to show that not only do extreme athletes often experience absent periods, but women exercising at regular levels can experience subtle changes in their menstrual cycle that may be difficult to notice, but may decrease fertility. Since exercise is definitely recommended for all women, including during pre-conception and pregnancy, it’s worth discussing with your physician whether your regimen is too lax, too intense or may be affecting fertility.
The good news is that weight-improvement interventions can result in relatively high spontaneous pregnancy rates, and fertility treatment can help most of the women still having difficulty. Improving your lifestyle is not only beneficial to fertility, but also to the long-term health for you and your baby. This is an investment worth making! Creating a healthy lifestyle while growing your family can be a strong bonding and empowering experience for a couple, and for straight couples, being overweight or having an unhealthy lifestyle can certainly diminish male fertility as well.
At CCRM, we strongly encourage our patients to take stock and work with their care team to create a lifestyle plan that maximizes their health as relates to weight and nutrition. Often times, this includes identifying stress, anxiety or depressive forces that lead to less healthy choices, and our mental health team is definitely available to help explore these concerns. Don’t be afraid to bring up these questions in your next visit, and explore what aspects of your fertility care you can positively influence!