Reasons women might switch birth control methods, and how to do so safely.
Another factor that puts some women at risk of an unintended pregnancy is the false belief that one must wait until the beginning of a menstrual cycle to start a new method. These gaps in protection should never occur, said Dr. Lesnewski, who was an author of a report on preventing contraceptive gaps in American Family Physician last year.
“Many women get pregnant when they stop one birth control method before starting another,” she said. For example, a woman who has been on the pill should not wait for the start of her next period before she begins a different pill. Rather, she should switch directly from one pill to another without missing a day.
For other kinds of changes — say, from a pill to a contraceptive patch — a two-day overlap is needed to prevent a decline in hormone levels and assure contraceptive protection. When switching from a pill, patch or vaginal ring to a progestin IUD or hormonal implant, an overlap of seven days is needed, but no overlap is required if switching to a copper IUD.
On the other hand, if the switch is made in the opposite direction — from a copper IUD to a pill, patch or ring — a woman should use the new method for seven days before the IUD is removed.
Another option is to rely, religiously, on a barrier method of contraception, like a condom or diaphragm with spermicide, to cover any gap in protection. Use of a barrier method for seven days is essential when changing from a copper IUD to a progestin IUD (or for four days when making a switch in the opposite direction) because a woman can become fertile as soon as an IUD is removed.
The Reproductive Health Access Project has posted a chart that spells out in great detail how to switch contraceptives while minimizing the risk of pregnancy. It can be found at www.reproductiveaccess.org/fact_sheets/switching_bc.htm.
I wish my young friend had had access to this sort of information. But I suspect she is not alone in believing that despite no contraception she would not get pregnant.
Those of you who still think the same, consider this: Among fertile women who have regular intercourse without birth control, the conception rate approaches 100 percent within two years.