Should birth control be initiated at the start of menstruation?

Birth Control Initiation Timing

Birth control can be started at any time during the menstrual cycle, and does not need to be initiated specifically at the start of menses, as long as it is reasonably certain that the woman is not pregnant. 1

Optimal Timing for Starting Birth Control

The U.S. Selected Practice Recommendations for Contraceptive Use provides clear guidance on when to start hormonal contraceptives:

Combined Hormonal Contraceptives (CHCs)

• Can be started any day of the menstrual cycle
• If started within the first 5 days of menstrual bleeding:
  • No backup contraception needed 1
• If started >5 days since menstrual bleeding began:
  • Need backup contraception (or abstinence) for 7 days 1

Progestin-Only Pills (POPs)

• Can be started any day of the menstrual cycle
• If started within the first 5 days of menstrual bleeding:
  • No backup contraception needed 1
• If started >5 days since menstrual bleeding began:
  • Need backup contraception (or abstinence) for 2 days 1

Quick Start vs. First-Day Start vs. Sunday Start

The FDA-approved labeling for combined hormonal contraceptives like Kariva® describes two common starting approaches 2:

1. Day 1 Start: Begin taking the first active pill on the first day of menstrual bleeding
2. Sunday Start: Begin taking the first active pill on the first Sunday after menstruation begins

However, the "Quick Start" approach (starting on the day of the healthcare visit regardless of cycle day) is also supported by evidence and may improve initial continuation rates 3.

Evidence on Effectiveness and Safety

Research shows that:

• Pregnancy rates do not differ based on when in the menstrual cycle contraceptives are initiated 1, 3
• Bleeding patterns and side effects are similar regardless of when contraceptives are started 3
• No ovulations were observed when COCs were started at a follicle diameter of 10 mm (approximately cycle day 7-8) 3

Special Circumstances

Postpartum (Not Breastfeeding)

• Can start immediately postpartum (after 3 weeks for CHCs due to VTE risk) 1
• If ≥21 days postpartum and no return of menses:
  • Need backup contraception for 7 days (CHCs) or 2 days (POPs) 1

Postabortion

• Can start immediately after abortion 1
• No backup needed if started at time of surgical abortion 1
• Otherwise, backup needed for 7 days (CHCs) or 2 days (POPs) 1

Common Pitfalls to Avoid

1. Unnecessary Delay: Waiting for the next menses to start contraception may leave women vulnerable to unintended pregnancy. The benefits of immediate start likely outweigh any risks 1.

2. Missing the Backup Period: Failing to use backup contraception when starting mid-cycle can lead to contraceptive failure.

3. Forgetting Special Circumstances: Different rules apply for postpartum, breastfeeding, and post-abortion situations.

4. Not Considering Pill Type: Lower-dose pills (20 mcg ethinyl estradiol) may be less effective at preventing ovulation when started later in the cycle compared to higher-dose formulations (30 mcg) 3.

In conclusion, while starting birth control during menses has traditionally been recommended, it is not necessary for contraceptive effectiveness. Starting immediately (Quick Start) is safe, effective, and may improve initial adherence while reducing the risk of unintended pregnancy that could occur while waiting for the next menstrual period.