Can you start an Oral Contraceptive Pill (OCP) if there's a risk of pregnancy?

Starting Oral Contraceptive Pills When There's Risk of Pregnancy

Oral contraceptive pills (OCPs) should only be started when it is reasonably certain that the woman is not pregnant. 1 If pregnancy cannot be ruled out, the benefits of starting progestin-only pills (POPs) likely exceed any risk, but combined oral contraceptives (COCs) should be avoided.

Determining Pregnancy Status Before Starting OCPs

Before initiating any OCP, it's essential to determine if there's a risk of pregnancy. The U.S. Selected Practice Recommendations for Contraceptive Use provides clear guidance:

When Pregnancy Can Be Reasonably Ruled Out:

• Within first 7 days since menstrual bleeding started
• No sexual intercourse since last normal menses
• Consistently and correctly using a reliable method of contraception
• Within 7 days after spontaneous or induced abortion
• Within 4 weeks postpartum
• Fully or nearly fully breastfeeding, amenorrheic, and less than 6 months postpartum

Algorithm for Starting OCPs with Possible Pregnancy Risk

Step 1: Assess pregnancy likelihood

• If pregnancy can be ruled out → Start OCP immediately
• If pregnancy cannot be ruled out → Consider the following options:

Step 2: Choose appropriate action based on OCP type

• For Progestin-Only Pills (POPs):

  • Can be started immediately with a follow-up pregnancy test in 2-4 weeks 1
  • Benefits of starting POPs likely exceed any risk even with uncertain pregnancy status 1
  • POPs have minimal effects on an established pregnancy 2

• For Combined Oral Contraceptives (COCs):

  • Should NOT be started if pregnancy is possible
  • Estrogen component could potentially affect a developing pregnancy
  • Wait until pregnancy can be ruled out (next menstrual period or negative pregnancy test)

Back-Up Contraception Requirements

When starting OCPs with possible pregnancy risk:

For POPs:

• Use back-up contraception (condoms) or abstain from sexual intercourse for the first 2 days after starting POPs 1

For COCs (once pregnancy ruled out):

• If started within first 5 days of menstrual cycle: No back-up needed
• If started >5 days since menstrual bleeding: Use back-up contraception for 7 days 1

Special Considerations

Postpartum Women

• Breastfeeding women:

  • POPs can be started immediately postpartum (U.S. MEC 2 if <1 month, U.S. MEC 1 if ≥1 month) 1
  • COCs not recommended until at least 6 weeks postpartum due to effects on milk production 3

• Non-breastfeeding women:

  • POPs can be started immediately postpartum (U.S. MEC 1) 1
  • COCs should be avoided before 21 days postpartum due to elevated VTE risk 3
  • From 21-42 days, COC use should be based on individual VTE risk assessment 3

Post-abortion Women

• POPs and COCs can be started immediately after abortion (U.S. MEC 1) 1
• No back-up contraception needed if started at time of surgical abortion 1

Common Pitfalls to Avoid

1. Delaying POP initiation unnecessarily: POPs can be started immediately even with uncertain pregnancy status, with follow-up testing.

2. Failing to provide adequate back-up contraception: Ensure patients understand when and for how long back-up methods are needed.

3. Overlooking postpartum VTE risk: COCs should not be used in the immediate postpartum period due to increased thromboembolism risk.

4. Ignoring the impact of vomiting/diarrhea: These conditions can reduce OCP effectiveness. If they occur, advise continuing pills but using back-up contraception until 7 consecutive days of successful pill-taking after resolution. 1

5. Not considering over-the-counter options: For those with limited healthcare access, over-the-counter progestin-only pills (like Opill containing norgestrel 0.075 mg) are now available with a Pearl Index of 4.4 (95% CI, 1.9-8.8). 4

By following these evidence-based guidelines, healthcare providers can help patients safely initiate oral contraception while minimizing pregnancy risk and ensuring optimal contraceptive effectiveness.