Weight is a sensitive subject, especially for women. Aside from how weight affects physical appearance and self-esteem, an unhealthy weight can impact a woman's fertility, how she responds to treatment, the course of her pregnancy and the health of her child. An unhealthy weight means being either overweight or underweight.
What is considered a healthy weight?
Clinicians use the Body Mass Index (BMI) to determine whether someone is underweight, overweight or "normal." BMI is measured by dividing a person's weight in kilograms by the square of the person's height in meters. The normal range for a BMI is between 18.5 to 24.9; less than 19 is considered underweight, 25 to 29 is deemed overweight and greater than 30 is categorized as obese.
You can use this handy chart, developed by the National Institute of Health, to calculate your BMI and learn where you call on the range: https://www.nhlbi.nih.gov/health/educational/lose_wt/BMI/bmicalc.htm
How weight affects fertility?
Many overweight and underweight women get pregnant without experiencing any problems trying to conceive. But getting pregnant is not so easy for approximately 12 percent of women with infertility who weigh too much or too little.
Overweight women tend to produce excessive estrogen, which acts like birth control, while underweight women produce too little. Additionally, an abnormal weight can cause irregular ovulation.
Underweight women may have ovulatory problems because of a poor diet with insufficient nutrients combined with excessive exercise. Frequently their periods completely cease, resulting in amenorrhea.
Being overweight is a common characteristic of Polycystic Ovary Syndrome (PCOS). PCOS sufferers are predisposed to insulin resistance, which causes the ovaries to make excessive testosterone. This, in turn, results in irregular or scanty ovulation.
Weight and IVF Treatment
Weight also plays a role in treatment success in several different ways. A recent study found obese women need an increased dosage of gonadotropins to successfully harvest their eggs. Overweight women also produce lower quality eggs; in fact, when they use donor eggs, their IVF success rates are similar to women with a normal BMI using their own eggs.
Weight and Pregnancy
The impact of weight continues into pregnancy. Overweight pregnant women are at a higher risk for developing complications, such as preeclampsia and gestational diabetes, as well as experiencing miscarriages and early term births. The babies of underweight women are more likely to be underweight themselves.
We advise women attempting pregnancy to prepare themselves by establishing healthy eating and exercise patterns so they will fall within the normal BMI range. Additionally, it is a good idea to visit their primary to see if they have any medical conditions that could affect weight, such as thyroid disease or diabetes.
Reaching the goal of a normal BMI will insure that weight won't stand in your way of getting pregnant and delivering a healthy baby.