What contraceptive method should a non‑smoking woman under 35 years old with no contraindications start?

Starting Birth Control for a Healthy Non-Smoking Woman Under 35

For a healthy, non-smoking woman under 35 with no contraindications, long-acting reversible contraceptives (LARCs)—specifically the levonorgestrel intrauterine device (LNG-IUD) or subdermal etonogestrel implant—should be offered as first-line options due to their superior effectiveness (failure rates <1% per year), followed by combined hormonal contraceptives if the patient prefers a short-acting method. 1

Recommended Contraceptive Hierarchy

First-Line: Long-Acting Reversible Contraceptives (LARCs)

• The CDC recommends LARCs as the most effective reversible contraceptive options with typical-use failure rates of 0.05%–0.6% per year, compared to 9% for combined oral contraceptives. 1

• LARCs eliminate user-dependent failure since they require no daily or weekly action after insertion. 1

• Both the LNG-IUD and subdermal implant are Category 1 (no restrictions) for women under 35 based on age alone. 2

Subdermal Etonogestrel Implant

• Can be inserted at any time if reasonably certain the patient is not pregnant 1
• Requires backup contraception for 7 days if inserted >5 days after menses started 2, 1
• No examination is required before insertion 1
• Fully effective for 3 years 3

Levonorgestrel Intrauterine Device (LNG-IUD)

• Can be inserted at any time if reasonably certain the patient is not pregnant 2
• Requires backup contraception for 7 days if inserted >7 days after menses started 2
• Requires bimanual examination and cervical inspection before placement 2, 1
• Effective for 3–8 years depending on formulation 2

Second-Line: Combined Hormonal Contraceptives (CHCs)

If the patient prefers a short-acting method or declines LARCs:

Pre-Initiation Requirements

• Blood pressure measurement is mandatory and is the ONLY required examination before starting CHCs 2, 1, 4, 5
• No pelvic examination, Pap smear, or STI screening is required to initiate CHCs 2, 1

Recommended Formulation

• Start with a low-dose monophasic combined oral contraceptive containing 30-35 μg ethinyl estradiol with levonorgestrel 4
• This formulation has extensive safety data and lower androgenic effects 4
• Any pill with ≤35 μg ethinyl estradiol is Category 1 (no restrictions) for women under 35 4

Initiation Protocol

• Use "quick start" same-day initiation without waiting for menses 4
• If started >5 days after menses began, use backup contraception (condoms or abstinence) for 7 days 2, 4

Typical-Use Effectiveness

• Failure rate is approximately 9% with typical use, 0.3% with perfect use 4, 5

Third-Line: Other Hormonal Options

Progestin-Only Pills (POPs)

• No examination required before initiation 2, 1
• Backup contraception needed for 2 days (norethindrone/norgestrel) or 7 days (drospirenone) if started >5 days after menses 1
• Typical-use failure rate similar to CHCs (~9%) 5

Depot Medroxyprogesterone Acetate (DMPA)

• No examination required before initiation 2
• Requires clinic visits every 3 months for reinjection 1
• Typical-use failure rate approximately 6% 1

Critical Safety Screening

Absolute Contraindications to Combined Hormonal Contraceptives

Screen for these conditions before prescribing CHCs:

• History of venous thromboembolism or pulmonary embolism (Category 4—absolute contraindication) 1
• Severe uncontrolled hypertension (systolic ≥160 mmHg or diastolic ≥100 mmHg) 4
• Migraine with aura (Category 4—absolute contraindication) 6
• Smoking ≥15 cigarettes/day if age ≥35 years (Category 4) 2
• Active or recent breast cancer 2
• Complicated valvular heart disease 4
• Current hepatic dysfunction 4

Important Clinical Pearls

• Smoking status is the most critical factor to assess, as CHCs become contraindicated at age ≥35 in smokers 4, 7
• For non-smokers under 35, the absolute cardiovascular risk with CHCs is very low 7
• Baseline VTE risk increases from 1-5 per 10,000 woman-years to 3-4 per 10,000 woman-years with CHC use, which is substantially lower than pregnancy-related VTE risk of 10-20 per 10,000 woman-years 4

Non-Contraceptive Benefits of CHCs

Counsel patients about additional health benefits: 4, 5, 8

• Decreased menstrual cramping and blood loss 4
• Improvement in acne 4
• Protection against endometrial and ovarian cancers with use >3 years 4, 8
• 90% reduction in ectopic pregnancy risk 8
• 50% reduction in pelvic inflammatory disease 8
• 40% reduction in dysmenorrhea 8

Drug Interactions to Screen For

The following medications reduce CHC effectiveness and require alternative contraception or backup methods: 4

• Rifampin or rifabutin
• Certain anticonvulsants (phenytoin, carbamazepine, barbiturates, primidone, topiramate, oxcarbazepine)

Note: Broad-spectrum antibiotics, antifungals, and antiparasitics do NOT reduce CHC effectiveness 4

Common Pitfalls to Avoid

• Do not delay contraceptive initiation to await STI screening results unless purulent cervicitis is visible 1
• Do not require a pelvic examination before starting CHCs, implants, POPs, or DMPA—only blood pressure is needed for CHCs 2, 1
• Do not wait for the next menstrual period to start contraception—same-day "quick start" is recommended 4
• Do not exclude patients with obesity (BMI ≥30) from any contraceptive method—all methods can be used without restriction 1