Significance

• The Centers for Disease Control and Prevention (CDC) estimates that in 2001, about half of all pregnancies in the United States were accidental. Although the pill does an excellent job preventing pregnancy, some women become pregnant while taking it because of missed pills, drug interactions and timing errors.
  
  

Types

• Most birth control pills consist of a low dose of synthetic progestin and estrogen hormones, but low-dose, or mini-pills, contain only progestin and are generally prescribed to nursing mothers or women who cannot take synthetic estrogen. A new birth control pill option is the extended-cycle pill that limits women's menstrual cycles to four per year instead of the normal 13.
  
  

Time Frame

• Women on an extended cycle pill might be slightly less likely to realize they are pregnant than those who have monthly cycles. However, most women realize that they are pregnant within a month and discontinue pill use at that point. Years of studies of women who have taken birth control pills in early pregnancy have yet to indicate any serious issues such as birth defects or miscarriage connected to their use in the first trimester.
  
  

Considerations

• Although no research indicates links between birth defects and hormonal pill use during pregnancy, a 2009 study found increased incidents of low birth weight and preterm labor in women who used the pills during conception. If you suspect you are pregnant, see your practitioner as soon as possible. Discontinue pill use immediately if you're pregnant.
  
  

Prevention/Solution

• By making sure you do not miss or skip pills, and that you avoid any drug interactions that could result in birth control failure, doctors believe women can significantly reduce their pregnancy rate while on hormonal birth control. Although the health consequences of becoming pregnant on the pill are not dire for moms or babies, recent research by the March of Dimes indicates that the healthiest pregnancies and babies are those that are planned.
  
  

Misconceptions

• Many women are concerned that birth control pills will cause a false positive on a pregnancy test, but that is not true. Although birth control pills contain estrogen and progesterone, pregnancy tests pick up human chorionic gonadotropin, or hCG. HCG is only present in the urine when pregnancy occurs; it is not something found in birth control pills.