Overweight Women Who Get IVF Risk High Miscarriage
Women who are overweight should be warned during fertility counseling about their increased risk of miscarriage. A new study shows that overweight women are more than twice as likely to have a miscarriage if they get pregnant through in vitro fertilization (IVF) than women who have a healthy weight.
IVF refers to a process in which a number of eggs are stimulated to develop during a woman’s menstrual cycle. The eggs are retrieved from the ovary under ultrasound guided needle puncture and transferred to a lab, where they are fertilized with sperm (the husband’s/partner’s or other donor). The fertilized eggs are allowed to develop in a special culture medium, and the embryos that result and then placed into the uterus.
According to the American Pregnancy Association, the success rate of IVF clinics depends on many factors, including a patient’s characteristics and the treatment approach used. However, the live birth rate for each IVF cycle started is about 30 to 35 percent for women younger than 35, 25 percent for women ages 35 to 37, 15 to 20 percent for women ages 38 to 40, and 6 to 10 percent for women older than 40.
Women who conceived naturally have a greater chance of miscarriage if their body mass index (BMI) is 25 or greater. “Overweight women wishing to get pregnant by spontaneous conception are already counselled to lose weight before trying for a baby,” according to Tarek El-Toutkhy, a fertility specialist who led the study at Guy’s and St. Thomas’ Hospital in London.
Overweight women are at greater risk of developing conditions that can jeopardize their pregnancy, including diabetes, premature delivery, pre-eclampsia, high blood pressure, and post-partum bleeding. To identify the risks associated with IVF among overweight women, El-Toukhy’s team examined the medical records of 318 women who under IVF over a four-year period.
The women were divided into two groups: 186 had a healthy BMI between 18.5 and 24.9, while 133 had a BMI of 25 or greater. Nineteen women in the latter group were obese, which is a BMI of 30 or higher. All of the women had one embryo transferred.
The miscarriage rate among women with a healthy BMI was 22 percent compared with a 33 percent miscarriage rate among overweight women. After the authors adjusted the data to take into account the women’s age, history of infertility and miscarriage, and lifestyle factors, they concluded that overweight women had more than double the risk of having a miscarriage.
Although other studies have looked at the question of miscarriage in IVF and overweight women, they tended to be complicated by several factors, including implanting several embryos at the same time at different stages of development. This study eliminated that complication by using only one embryo at one stage of development.
Overweight women who are considering IVF should be aware that they are at more than twice the risk of having a miscarriage than if they were at a healthy weight. This knowledge can allow them to take steps to achieve a healthy weight before undergoing IVF.
American Pregnancy Association
Guy’s and St. Thomas’ Hospital in London