Women's Health

Last week we talked about this frequently posed question: “How long will it take to get pregnant after stopping a method of birth control?” Today, we will look at how the Pill affects women who are trying to conceive.

Fertility and Birth Control Pills
There are two basic types of oral contraceptives. The progestin-only pill (also known as the “mini pill”) contains only a low dose of synthetic progesterone – no estrogen. In a British study (Hassan, 2004), women that discontinued the “mini pill” to conceive had an average of about 6 months until pregnancy occurred. This is not a statistically significant difference from women who use condoms.

The second type of oral contraceptive is the more commonly used combined oral contraceptive (COC). It contains both synthetic estrogen and synthetic progesterone. COCs have been used in the USA for more than fifty years and have undergone significant decreases in the amounts of hormones. Some of the earlier COCs had 100 micrograms of estrogen. Compare this to 20 micrograms of estrogen in pills today!

The dose of estrogen may have an impact on time to conception after stopping a COC. Overall, Bracken (1990) found that it took about 6 months to conception in prior COC users – compared to 3.6 months among women using other types of birth control. When the women using pills of 50 micrograms estrogen (or more) were contrasted to women using lower estrogen pills, the higher dose pills had the greatest conception delays. Yet over time, high and low dose COCs both show a similar reduced risk of infertility (Bagwell, 1995).

So is there a difference in time to conception between women who use COCs for a short vs. long duration? In a population drawn from the famous Nurses’ Health Study, there was no increased risk of delayed fertility linked to either long-term use or younger age at initial use (Chasan-Taber, 1997). Comparing 925 COC users, short-term users (less than two years of use) vs. long-term (greater than two years of use), Hassan (2004) found a difference in time to pregnancy. Short-term users averaged 4.5 months to conception while long-term users averaged 8.5 months. Interestingly, 60% of COC users took the Pill for longer durations.

Remember we discussed the role of advancing age for women trying to get pregnant? The effect of COCs on extended time to pregnancy was more pronounced in women as they aged (Hassan 2004 & Bracken, 1990).

Next week we will take a closer look at fertility and IUDs.

Read the series:

• Part 1: Getting Pregnant After Birth Control
• Part 2: Getting Pregnant After Stopping the Pill
• Part 3: Getting Pregnant After Stopping IUDs
• Part 4: Getting Pregnant After Depo, Implanon, Ortho Evra Patch and Nuva Ring

Comment on this post and ask Jane your questions on the Gynecology Exchange.