Obesity is one of the most common and well-documented risk factors affecting fertility in both men and women. Weight plays a vital role in fertility. To get pregnant, the woman must neither be overweight or underweight. If she is close to a healthy weight, then the chances of getting pregnant and having a healthy baby are high.
What is Obesity?
Obesity is a metabolic disorder where a person has an excessive accumulation of body fat. When the intake of calories is more and not burned through daily activities and exercise, the excess calories get stored in the body as fat. Excess weight is associated with many adverse health consequences. It has detrimental influences on reproductive health and negatively affects fertility.
BMI (Body Mass Index) & pregnancy
A recent study has found that the higher a woman`s BMI (Body Mass Index), there are fewer chances of her getting pregnant. To calculate body fat, BMI uses height and weight. When the BMI (weight by height) is between 20 to 25, it indicates normal body weight, and chances of getting pregnant are easy. If the BMI is less than 19, then it is considered underweight. A BMI between 25 to 29 means you are overweight and greater than 30 means you are obese. With a BMI above 25, the chances of getting pregnant are low, and responding positively to fertility treatments is also lower.
Hence, BMI must neither be too high nor too low, as it is associated with fewer chances of getting pregnant in women. Body mass affects fertility issues by causing menstrual disturbance and anovulation. One of the best things to improve fertility is to obtain a healthy normal weight.
How does obesity affect my ability to get pregnant?
Many research studies report that women who are obese or overweight tend to have difficulty getting pregnant. There is a link between obesity, infertility, and excess insulin production – a medical condition called PCOS (Polycystic ovary syndrome). It is one of the reasons affecting fertility and causing obesity. Overweight and obesity affect fertility by:
Preventing ovulation – Excess weight is linked to insulin resistance and decreased levels of proteins regulating hormones like androgen and estrogen. Fat cells in the body of obese women produce higher estrogen levels, which works against the body when it’s trying to ovulate.
Obesity causes hormonal imbalances affecting the menstrual cycles and no egg is released by the ovaries. Thus, women with high BMI are unable to conceive because they don`t ovulate.
Preventing fertility treatments from working – Studies show that obesity contributes to reduced response to fertility treatments. Obesity lowers the success rate for women undergoing fertility treatments, such as in-vitro fertilization (IVF) owing to poor oocytes quality, lower preimplantation rate, and uterine receptivity.
As obesity lowers the chances of getting pregnant with fertility treatments, it is highly recommended for obese women to lose weight to improve their fertility functions.
Impact of obesity affecting fertility treatment
Though fertility treatments may increase fertility, it is still less effective in cases of obese couples. Obese women have shown poorer outcomes to treatments like IVF (In vitro fertilization) where higher doses of medications are given to induce ovulation or stimulate the ovaries for IVF. When gonadotrophins are used for ovulation induction in obese women undergoing IVF, analysis confirms obesity impairs ovarian responsiveness to gonadotrophin stimulation.
For women undergoing ART (Assisted Reproduction Technology), studies have linked obesity with negative ART outcomes where fewer oocytes are collected, fertilization rates are poorer, higher miscarriage rates, and reduced pregnancy rates.
Weight loss to increase fertility
Weight loss in anovulatory obese women is extremely effective for the regularizing menstrual cycles, resumption of ovulation, improvement of spontaneous pregnancy rate, and reduction of miscarriage rate.
Developing healthy habits of a balanced diet and regular exercise regimen can help in gradually losing weight. Going on crash diets has detrimental effects on health.
Obesity and male infertility
In obese men, the fat cells convert a male hormone (androstenedione) into the female hormone estrone, which affects the metabolism of the part of the brain that regulates testicular function. Thus, this can impair fertility function in men.
Obese men have low or no sperm counts that happen due to many reasons like: Elevated body temperatures, especially in parts like the scrotum. Hormonal imbalances result in higher estrogen levels, low testosterone levels, reduced spermatogenesis. These factors may favor infertility.
Obesity affects female infertility
In women, health conditions like PCOS (Polycystic ovary syndrome) are one of the common causes of infertility. Most women who have PCOS are affected by obesity which aggravates infertility through irregular menstrual cycles, affects ovulation and pregnancy rates.