Interview has been edited for clarity.
How does obesity impact your cycle and your hormones?
According to Dr. DeTata, the relationship between fat cells, the ovaries, reproductive hormones, and the menstrual cycle is very complex.
“Fat cells are more than just storage places for extra energy. They can make substances that affect ovarian production of hormones, and they can change the hormones made by the ovaries so that they act differently in the body. Estrogens and progesterone — hormones made by the ovaries — can affect the fat cells themselves, and they can also act on the brain to change behavior that may lead to changes in activity and eating that can increase or decrease weight.
“To make this even more complicated, there are other things that influence hormones, such as genetics, stress, age, sleep, environment, and probably other factors that we do not understand yet.”
The connection between obesity and polycystic ovarian syndrome (PCOS)
Polycystic ovarian syndrome is a common cause of irregular menstrual periods and infertility, says Dr. DeTata. It can also be associated with heavy bleeding, acne, male pattern hair growth, and storing fat around the midsection.
“Along with the menstrual cycle and infertility problems that PCOS causes, it can also impact a person’s health over their lifetime. People with PCOS are more likely to have type 2 diabetes, hypertension, cardiovascular disease, and endometrial cancer.”
Dr. DeTata says that not everyone with PCOS is obese. In fact, 60 percent of people with PCOS are obese, but the other 40 percent are either normal weight or underweight.
“Obese or not, PCOS is associated with insulin resistance, increasing the risk of diabetes. There are insulin receptors on the ovaries, and when obese person become more obese, their PCOS worsens,” she explains.
Some diabetes medications can improve fertility and make menstrual cycles more regular in people with PCOS. For people who are overweight or obese, losing weight also improves ovulation and the regularity of menstrual cycles and decreases infertility, according to Dr. DeTata.
Which is more dangerous, obesity in pregnancy or pregnancy after bariatric surgery?
Dr. DeTata says that it depends on the degree of obesity and the type of weight-loss (or bariatric) surgery.
“Obesity can lead to many problems with pregnancy, and the risk increases with BMI.
“BMI, or body mass index, is a measure of your weight in comparison to your height. BMI has a few different categories. A BMI between 18–24 is normal; between 25–30 is overweight; and a BMI over 30 is considered obese. Pregnancies become more dangerous as BMI increases. There are several different types of surgery for obesity. Some surgeries are linked to more nutritional deficiencies, which can complicate pregnancy.”
Dr. DeTata advises talking to your health care provider before surgery about your plans to have a baby so you can go over the pros and cons of each type of surgery.
How soon is it safe to get pregnant after bariatric surgery?
Most people lose weight rapidly during the first 12–18 months after bariatric surgery. Dr. DeTata says it’s best to avoid pregnancy until your weight loss reaches a plateau. Many people find that their overall well-being increases with weight loss and exercise.
“Losing weight makes it easier to exercise, and more exercise makes it easier to lose weight,” she says.
If you have struggled with infertility, or haven’t thought about birth control previously, it’s important to remember that losing weight may increase your fertility. “It’s a good idea to use contraception until you‘re ready to conceive,” she says.
How to prepare for pregnancy after bariatric surgery
According to Dr. DeTata, pregnant people may have vitamin deficiencies, most commonly iron, vitamin B12, calcium, and folic acid. Deficiencies should be identified with blood tests and corrected before trying to conceive.
“It’s important to have adequate folic acid before trying to have a baby because deficiency of folic acid is associated with a type of severe birth defect called neural tube defects.These birth defects develop between 2 and 9 weeks after conception, which means that the problem has already occurred by the time the patient shows up for their first prenatal visit,” Dr. DeTata explains.
Dr. DeTata says obesity increases the likelihood of diabetes and hypertension and that people considering pregnancy need to be evaluated for medical illness, in order to treat these problems before getting pregnant. “The good news is that losing weight can make some of these problems go away.”
Things to remember
You can safely get pregnant after bariatric surgery if you plan ahead and take steps to maximize your health before trying to get pregnant.
Overall, the risks of pregnancy after bariatric surgery are low if nutritional deficiencies are corrected. It’s best to wait at least 12–18 months after surgery, until weight loss has plateaued.
Make sure to discuss your pregnancy plans with your health care provider so that you can work together for the best outcome.
History of updates
Current version (15 November 2021)
Medically reviewed by Dr. Cynthia DeTata, Clinical assistant professor of obstetrics and gynecology, Lucile Packard Children's Hospital, California, US