Table 2 Development of the infertility question

Original question^a,c

• “Have you ever had a period of 12 months when you did not get pregnant even though you were having regular sexual intercourse and not doing anything to prevent pregnancy? Include times when you weren’t trying to get pregnant. Regular intercourse includes having sex at least 3 times per month.”

Intermediate questions^b,c

• “Have you ever had sexual intercourse with a male partner?”

• “Have you ever tried to get pregnant for 6 months or more? Only count months when you had unprotected sex with a man at least 3 times per month with the intention of getting pregnant.”

• “Now, think about times you were not trying to become pregnant. Was there ever a period of 6 months or longer when you were having regular intercourse with a man and doing nothing to prevent pregnancy but you did not become pregnant? Regular intercourse means at least 3 times per month.”

Final question^c

• “Have you ever had sexual intercourse with a male partner?”

• “Has there ever been a period of time during which you had unprotected sex with a male partner for 6 months or longer but you did not get pregnant? Only count periods of time when you had sex at least 3 times a month.”