Study: Birth control pills just as effective for obese women
August 13th, 2010 by Jennifer Walker-Journey
Obese women have just the same protection against getting pregnant while taking birth control pills as normal-weight women, according to a study published in a recent edition of the American College of Obstetrics & Gynecology’s green journal. This finding puts into question previous studies that have suggested that obese women required higher doses of oral contraceptives for the pills to be as effective as in normal-weight women.
Birth control pills increase a woman’s risk of life-threatening blood clots, a condition obese women are already at greater risk for than normal-weight women. Birth control pills with higher estrogen levels put women at even greater risk for developing blood clots, which can lead to deep vein thrombosis, pulmonary embolism, heart attack, stroke and even death. Thus, prescribing high-dose birth control pills to obese women can be dangerous.
The clinical trial involved 226 normal-weight or obese women who were randomly assigned to take pills with either a lower or higher estrogen dosage. All women underwent blood tests to determine if they were using the pills consistently. After three or four cycles, the women received multiple ultrasounds and blood tests to determine if their ovaries were making eggs. About 90 percent of normal-weight women and 72 percent of obese women had hormone levels that indicated consistent use.
Of the remaining 150 women who used the oral contraceptives regularly, three out of the 96 normal weight women conceived compared to one out of the 54 obese women, leading researchers to determine that obese women were just as protected against unwanted pregnancies while on the pill as normal-weight women.
This fall, the National Institutes of Health will convene a group of experts to investigate whether further research is necessary on obesity and oral contraceptives. Meanwhile, the Food and Drug Administration plans to hear evidence that a new emergency contraceptive pill is less effective in obese women.