The Correlation Between BMI And Fertility
When most people think about the relationship between weight and fertility, the mind almost always goes to the negative associations between being overweight or obese and problems with conception and pregnancy complications. And while the correlation is correct, being underweight can be equally problematic for women trying to conceive or successfully carry a pregnancy to term.
The link between low BMI and irregular menstrual cycles
Physicians usually rely on BMI to determine if a woman is underweight, in a normal weight range, overweight, or obese. A normal BMI is between 19 and 24, and BMI scores under 19 are considered underweight. Researchers and physicians have noted that underweight women often experience irregular menstrual cycles.
How irregular menstrual cycles impact fertility
Underweight women don’t have a healthy amount of fat cells. As a result, the body may go into what is known as “starvation mode.” When a starvation mode is activated, the body begins producing 2-hydroxy estrone, an anti-estrogen, and the substance can cause the reproductive system to shut down. A common side effect is that ovulation can be inconsistent, or in extreme cases, menstruation may stop altogether. Difficulty tracking ovulation or not even having a period can make conceiving naturally very difficult.
Difficulties with pregnancy
Just as with trying to conceive, being underweight can create complications during pregnancy. The most pressing concerns are that an underweight woman may have a preterm birth where the baby is born before 37 weeks. Additionally, the baby may have a lower birth weight of less than five and a half pounds. More importantly, low birth weight babies are more at risk for health and developmental problems. Underweight women who conceive are encouraged to gain between 28 to 40 pounds during pregnancy.
Planning for Success
The human body relies on a delicate balance to function correctly, including the reproductive system. Being outside of the recommended normal BMI range can make conceiving difficult and create additional issues if a woman can get pregnant. Experts recommend that underweight women strive to gain two to five pounds before conceiving. Additionally, while many women lose weight in the first trimester because of morning sickness, underweight women are encouraged to focus on gaining two to five pounds during that time. Underweight women that want to conceive should speak with a physician to determine the proper course of action to improve the chance of successful outcomes. Also, consider talking with a dietician to outline healthy high-calorie foods to incorporate into a daily diet.