What is the recommended protocol for initiating contraception in a reproductive‑aged woman, including screening for estrogen contraindications and selecting an appropriate method?

Initiating Birth Control in Reproductive-Aged Women

Start any contraceptive method immediately if you are reasonably certain the patient is not pregnant—no need to wait for the next menstrual period, and minimal examinations are required before initiation. 1

Pre-Initiation Screening Requirements

The required examinations before starting contraception are minimal and method-specific:

Combined Hormonal Contraceptives (Pills, Patch, Ring)

• Blood pressure measurement only 1
• No pelvic examination required 1
• No breast examination required 2
• No weight/BMI, glucose, lipid, or liver enzyme testing needed 2
• No recent Papanicolaou test required 3

Progestin-Only Methods

• No examination required for progestin-only pills, DMPA injection, or implant 1, 2
• Blood pressure measurement not needed 2

Intrauterine Devices (IUDs)

• Bimanual examination and cervical inspection required 1
• Most patients do not require additional STI screening at time of placement 1

Screening for Estrogen Contraindications

Identify Category 3 and 4 contraindications to combined hormonal contraceptives through medical history alone 4:

Absolute Contraindications (Category 4)

• History of venous thromboembolism, stroke, or myocardial infarction 5, 4
• Active or history of breast cancer 6
• Migraine headaches with aura 4
• Age >35 years AND current smoking 5, 4
• Coronary artery disease or peripheral vascular disease 5
• Systemic lupus erythematosus with antiphospholipid antibodies 4
• Known liver impairment or active liver disease 2
• Diabetes with vascular complications 4

Relative Contraindications (Category 3)

• Uncontrolled hypertension 4
• Complicated valvular heart disease 5

Common pitfall: Studies show 39% of women with medical contraindications to estrogen still use combined hormonal contraceptives inappropriately, increasing cardiovascular risk 4. Always screen for these conditions before prescribing.

Method Selection Algorithm

Step 1: Rule Out Estrogen Contraindications

• If any Category 3 or 4 contraindication present: Offer progestin-only methods (pills, DMPA, implant, LNG-IUD) or copper IUD 5, 4
• If no contraindications: All methods available, including combined hormonal contraceptives 1

Step 2: Consider Patient Age

• Age <40 years: All methods appropriate if no contraindications 1
• Age 40-45 years: Natural estrogens preferred over synthetic ethinyl estradiol if combined hormonal contraceptives chosen 7
• Age >45 years: Progestin-only methods or IUDs preferred; combined hormonal contraceptives are Category 2 (generally can use) but cardiovascular risk increases 1

Step 3: Present Most Effective Methods First

Use tiered counseling—present long-acting reversible contraceptives (LARCs) before less effective methods 1:

1. Most effective: IUDs and implants (>99% efficacy) 1
2. Highly effective: DMPA injection, combined hormonal contraceptives (91-94% typical use) 1
3. Less effective: Barrier methods (condoms 82% typical use) 1

Timing of Initiation

Standard Initiation (Not Currently Pregnant)

Start immediately—do not wait for next menses 1, 3:

• Combined hormonal contraceptives: Start anytime; if >5 days after menses started, use backup contraception for 7 days 1
• Progestin-only pills (norethindrone/norgestrel): Start anytime; if >5 days after menses, use backup for 2 days 1
• Drospirenone progestin-only pill: Start anytime; if >1 day after menses, use backup for 7 days 1
• DMPA injection: Start anytime; if >7 days after menses, use backup for 7 days 1, 2
• Implant: Start anytime; if >5 days after menses, use backup for 7 days 1
• IUDs: Start anytime; LNG-IUD requires backup for 7 days if >7 days after menses; copper IUD provides immediate protection 1

After Abortion or Miscarriage

• First trimester: Start any method immediately within 5 days—no backup needed 1, 6
• If >5 days post-abortion: Wait for next menses and follow standard initiation timing 6
• Exception: Do not insert IUD after septic abortion 3

Postpartum Initiation

• Progestin-only methods: Start immediately postpartum 1, 3
• Combined hormonal contraceptives: Defer until 3-6 weeks postpartum due to venous thromboembolism risk 1
• Risk increases with: age ≥35 years, previous VTE, thrombophilia, immobility, BMI ≥30, postpartum hemorrhage, cesarean delivery, preeclampsia, or smoking 1

Practical Implementation

Prescribing Strategy

• Provide one year's supply of oral contraceptives, patches, or rings to reduce barriers and improve adherence 1, 3
• Make condoms readily available 1
• Consider telemedicine or patient portal counseling to eliminate unnecessary office visits 3

Follow-Up Documentation

Document: 1

• Patient understanding of method use, benefits, and risks
• Individualized follow-up plan
• Satisfaction with method and any concerns

Managing Common Side Effects

Unscheduled bleeding is the most common reason for discontinuation 1:

• Counsel that spotting/bleeding is common in first 3-6 months and generally not harmful 1
• Bleeding typically decreases with continued use 1
• If persistent and bothersome after 3-6 months, consider 3-4 day hormone-free interval (not during first 21 days of use) 1
• If unacceptable, offer alternative method 1

Drug Interactions to Consider

Certain medications reduce contraceptive efficacy 1:

• Anticonvulsants: phenytoin, carbamazepine, barbiturates, primidone, topiramate, oxcarbazepine (Category 3 for hormonal methods)
• Antimicrobials: rifampin or rifabutin (Category 3 for hormonal methods)
• St. John's wort (Category 2 for hormonal methods)
• Most antiretrovirals, SSRIs, and broad-spectrum antibiotics do not affect efficacy 1

Emergency Contraception Counseling

• Provide advance prescription for emergency contraceptive pills 8
• Levonorgestrel regimen more effective with fewer side effects than Yuzpe regimen 8
• Can use up to 5 days after unprotected intercourse; copper IUD up to 7 days 8
• Any contraceptive method can be started immediately after emergency contraceptive pills, with backup contraception for 7 days (14 days after ulipristal) 1