What Are the Causes of Decreased Birth Control Pill Absorption?

by Alexandra Haller

Overview

Millions of women successfully use birth control pills to prevent pregnancy each year. When you know how your behavior affects the effectiveness of the pill, you can take steps to ensure you don't have any complications.
Weight

In a study of 800 women sponsored by The National Institute of Child Health and Human Development, researchers found that overweight women (a BMI greater than 27) were 60 to 70 times more likely to become pregnant while on the pill. If you weigh more than 198 pounds, the pill may not be right for you.

Regularity

Women must take the pill consistently every day and, if possible, around the same time of day. When women take it without any predictable routine, the hormone levels in the body fluctuate, and therefore its efficacy at preventing pregnancy diminishes from a one in 100 chance to an eight in 100 chance, per Planned Parenthood.
Medicines

A few anti-seizure and HIV treatments, oral medicines that fight yeast infections, and Penicillin and tetracycline products may pose a slight risk of interference with oral contraceptives.
Herbs

According to the National Institutes of Health, women who have taken St. John's wort and birth control pills reported more unplanned pregnancies than women not taking this particular herb.
Illness

Excessive vomiting or diarrhea from a flu-like illness or food poisoning may adversely affect your birth control. If you have experienced a recent bout of illness, use a back-up method until you can talk with your doctor.

Overview