At what point in the menstrual cycle should oral contraceptive pills (OCPs) be started?

When to Start Oral Contraceptive Pills

Oral contraceptive pills can be started at any time during the menstrual cycle if pregnancy is reasonably excluded, but starting within the first 5 days of menstrual bleeding provides immediate contraceptive protection without requiring backup contraception. 1

Optimal Timing for Combined Oral Contraceptives (COCs)

Starting Within First 5 Days of Menses

• No backup contraception is needed when COCs are initiated within the first 5 days of menstrual bleeding. 1
• This timing aligns with the CDC's Selected Practice Recommendations and provides immediate contraceptive effectiveness. 1
• Research confirms that pregnancy rates do not differ based on timing of initiation, and no ovulations occur when starting by cycle day 5. 2

Starting After Day 5 of Menses

• If COCs are started more than 5 days after menstrual bleeding begins, backup contraception (such as condoms) must be used for 7 consecutive days. 1
• This 7-day window is critical because follicular activity increases as the cycle day advances, and ovulation suppression requires adequate time to establish. 2
• The evidence shows that while follicular activity increases with later cycle initiation, 7 days of pill use effectively inhibits ovulation. 2

Progestin-Only Pills (POPs) - Different Requirements

Timing Considerations for POPs

• POPs require only 2 days of backup contraception when started after day 5 of menses, compared to 7 days for COCs. 1
• If started within the first 5 days of menstrual bleeding, no backup contraception is needed. 1
• This shorter backup period reflects the rapid onset of POPs' contraceptive effects on cervical mucus, which occurs within approximately 48 hours. 3

Quick Start Method - Anytime Initiation

When Pregnancy is Reasonably Excluded

• Both COCs and POPs can be started at any time during the menstrual cycle if pregnancy is reasonably excluded, eliminating the need to wait for the next menstrual period. 1
• The CDC and ACOG explicitly advise against delaying contraceptive initiation until the next menstrual period, as this increases the risk of unintended pregnancy. 1
• When using Quick Start (initiating on the day of the healthcare visit), backup contraception is required for 7 days for COCs or 2 days for POPs. 1

Evidence Supporting Quick Start

• Research demonstrates that Quick Start may initially improve continuation rates compared to conventional starting strategies, though this difference diminishes over time. 2
• Bleeding patterns and side effects do not vary based on the timing of contraceptive initiation. 2

Special Clinical Scenarios

Amenorrhea (Not Postpartum)

• COCs can be initiated at any point if pregnancy is excluded, with 7 days of backup contraception required. 1
• POPs similarly can be started anytime with 2 days of backup contraception. 3

Postpartum Considerations

• Non-breastfeeding women can start COCs immediately postpartum, with backup contraception for 7 days if ≥21 days postpartum and menses have not returned. 4
• Breastfeeding women should consider alternative methods or delay COC initiation due to potential effects on lactation. 1

Common Pitfalls to Avoid

• Do not delay contraceptive initiation waiting for menses - this unnecessarily increases pregnancy risk and is not evidence-based. 1
• Do not confuse the backup contraception requirements - COCs require 7 days while POPs require only 2 days when started late in the cycle. 1
• Do not assume all hormonal contraceptives have the same initiation requirements - patches and rings follow similar rules to COCs (7 days backup if started after day 5), but POPs are different. 4