Your weight has substantial impact on your chance of obtaining pregnancy. This is the case for both the woman and the man. Both overweight and underweight reduce your chances.
The body mass index (BMI) is used as a measure of your weight in relation to your height (kg/m2). A BMI of 18.5-24.9 is within the normal range. A BMI of 25-29.9 is classed as overweight. If your BMI is above 30, you are classed as obese, and we prefer not to start treatment before you have lost weight.
- Height 1,70 m, weight 58 kg: BMI 20
- Height 1,70 m, weight 72 kg: BMI 25
- Height 1,70 m, weight 87 kg: BMI 30
- Height 1,70 m, weight 101 kg: BMI 35
A lot of overweight women have reduced fertility due to the influence of the fatty tissue and disruptions to the hormonal system. Many obese women have no or very rare menstrual periods and do thus not ovulate normally. Of course, this means that the woman does not become pregnant. Often, she will have what we call polycystic ovaries (PCO), which we will not describe in detail here. It may help the woman to know that her weight may be the cause of her PCO; however, the vicious circle should be broken.
If obese women become pregnant, they have:
- A higher risk of abortion
- A higher risk of developing diabetes during pregnancy
- A higher risk of having a complicated birth
Obese women need more hormones for follicle stimulation (and they are expensive), and oocyte aspiration is often more complicated. The reason for this is that the woman has a lot of fat on her intestines, which makes it difficult to see the ovaries and sometimes it is in the way during aspiration.
Consequently, obese women have a smaller chance of having a living, healthy child. To us, it is not just about getting the woman pregnant, but also about her having a living, healthy baby.
Women with a BMI above 30 loose at least 5-10 % of their weight. They should preferably reach a BMI below 30. This will often trigger ovulation and provide a better chance of good hormone stimulation with an adequate number of oocytes. If you are extremely obese, you must loose more than 10 %. Some will benefit from more exercise, using a gym, Weight Watchers, consulting their GP or joining a group.