What are the most suitable contraceptive options for an obese (Body Mass Index (BMI) of 35) adolescent female at increased risk of sexually transmitted infections (STIs)?

Contraceptive Recommendations for a 16-Year-Old Female with BMI 35 and High STI Risk

For this adolescent, recommend dual-method contraception: a long-acting reversible contraceptive (LARC)—specifically the etonogestrel implant or levonorgestrel IUD—combined with mandatory condom use at every sexual encounter. 1

Primary Contraceptive Method: LARC

The implant or hormonal IUD should be the first-line contraceptive choice because:

• LARC methods are appropriate for adolescents, including nulliparous women, with no age-related restrictions for the implant (Category 1 for ages <18 years) 1
• Obesity (BMI 35) is NOT a contraindication to any hormonal method or IUD—the 2024 CDC U.S. Medical Eligibility Criteria classifies all hormonal contraceptives and IUDs as safe for women with BMI ≥30 1
• LARC methods have the highest effectiveness with typical use: implant failure rate 0.05% and LNG-IUD 0.2%, compared to 9% for combined oral contraceptives 1
• LARC methods do not depend on daily adherence, which is critical for adolescents who have higher rates of inconsistent use with user-dependent methods 1

Why Not Combined Hormonal Contraceptives?

While combined hormonal contraceptives (pills, patch, ring) are medically safe for this patient (obesity alone is Category 1 for CHCs in adolescents) 1, they are less preferable because:

• Typical-use failure rate of 9% versus <1% for LARC 1
• Require daily adherence, which adolescents struggle with more than adults 1
• The patch may have reduced effectiveness in women >90 kg (198 lbs), though this patient's exact weight is unknown 1

Why Not Progestin-Only Pills?

Progestin-only pills should NOT be recommended for this patient because:

• POPs are less effective than other progestin-only methods (IUDs, implants, injectables) with typical-use failure rates around 9% 1, 2
• POPs require strict timing of administration relative to intercourse, making them inappropriate as first-line for adolescents 1, 2
• Better progestin-only options exist (implant, LNG-IUD) that don't require daily adherence 2

Mandatory Condom Use for STI Prevention

Condoms must be used at every sexual encounter regardless of the primary contraceptive method because:

• Hormonal contraceptives and IUDs provide NO protection against STIs including HIV, chlamydia, gonorrhea, and trichomoniasis 1
• Male latex condoms reduce STI transmission when used consistently and correctly, including HIV, gonorrhea, chlamydia, trichomoniasis, hepatitis B, herpes simplex virus, and human papillomavirus 1, 3
• This patient is at increased STI risk, making dual protection non-negotiable 1

Critical Counseling on Dual Method Use

Address the "LARC complacency" phenomenon directly:

• LARC users are 60% less likely to use condoms compared to oral contraceptive users, likely because they no longer perceive pregnancy risk 4
• Explicitly counsel that LARC prevents pregnancy but NOT infections—this distinction must be reinforced at every visit 1, 5
• Emphasize that condom use is for STI prevention, not backup contraception, to maintain motivation for consistent use 5, 4

Condom Use Instructions

Provide specific guidance on correct condom use 1:

• Use water-based lubricants only (K-Y Jelly, Astroglide)—oil-based products (petroleum jelly, massage oils, body lotions) weaken latex and cause breakage 1
• Latex condoms are preferred; polyurethane condoms are acceptable for latex sensitivity 1
• Natural membrane condoms do NOT protect against STIs and should never be used 1
• Female condoms are an alternative when male condoms cannot be used properly, though data are more limited 1

Implementation Algorithm

Step 1: Initiate LARC

• No physical examination required before LARC insertion 1
• Pregnancy test if sexually active or any possibility of sexual activity 6
• Insert implant or LNG-IUD at any time if reasonably certain not pregnant 1
• Backup contraception (condoms) for 7 days if not inserted during menses 6

Step 2: Condom Counseling

• Provide condoms at the visit and ensure accessibility 1
• Demonstrate correct use including lubricant selection 1
• Discuss negotiation strategies with partners about consistent use 5
• Address that STI risk exists even with one partner if partner history is unknown 1

Step 3: Emergency Contraception Backup

• Provide advance prescription or direct purchase information for levonorgestrel emergency contraception 1
• However, note that levonorgestrel EC loses effectiveness in women >165 lbs and is ineffective >176 lbs—ulipristal acetate may be more effective for this patient if weight exceeds these thresholds 1

Common Pitfalls to Avoid

• Do not assume LARC users will continue condom use—this requires explicit, repeated counseling 5, 4
• Do not prescribe oral contraceptives as first-line when LARC is medically appropriate—this prioritizes convenience over effectiveness 1
• Do not delay LARC insertion waiting for menses—it can be inserted anytime with appropriate backup 1
• Do not use spermicides (nonoxynol-9) in high STI-risk patients—they may increase HIV transmission risk 1, 7
• Do not recommend fertility awareness or withdrawal methods—these have unacceptably high failure rates for adolescents 1

Follow-Up Reinforcement

• Reassess condom use at every visit—ask specifically about frequency and consistency 5
• Screen for STIs regularly (at least annually, more frequently if indicated) 1
• Reinforce dual-method messaging at each encounter, as motivation for condom use may wane over time with LARC 5, 4