5.3 Emergency Contraception, Barrier Methods & Fertility Awareness-Based Methods
Key Takeaways
The Copper IUD and 52 mg Levonorgestrel IUS represent the most effective methods of emergency contraception (>99% efficacy) when inserted within 5 days (120 hours) of unprotected coitus, providing concurrent transition to long-term Tier 1 contraception.
Ulipristal acetate (Ella, 30 mg oral SPRM) maintains superior efficacy across the entire 120-hour window compared to oral levonorgestrel, inhibits ovulation even after the LH surge has begun, and remains efficacious in individuals with BMI ≥30 kg/m².
Starting hormonal contraception immediately after ulipristal acetate can reduce its efficacy, so patients wait at least 5 days before starting a hormonal method and then use barrier backup or abstain until 7 days after starting (about 12 days in total).
Barrier methods are the sole contraceptive modality providing protection against sexually transmitted infections; frequent use of the surfactant spermicide nonoxynol-9 induces vaginal mucosal disruption and paradoxically increases HIV acquisition risk.
Fertility awareness-based methods (FABMs) identify the fertile window (sperm survival ~5 days plus ovum survival ~24 hours); the symptothermal method combines cervical mucus monitoring with the post-ovulatory basal body temperature thermal shift (sustained 0.4°F–1.0°F elevation) driven by progesterone.
Emergency Contraception (EC) Comparative Efficacy Hierarchy
Emergency contraception (EC) provides postcoital pregnancy prevention following unprotected intercourse, sexual assault, or contraceptive failure. EC methods act before implantation; they do not disrupt an established pregnancy and are not abortifacients.
| Modality | Formulation & Dose | Approved Window | Mechanism of Action | Body Weight & BMI Impact | Ongoing Contraception Bridging |
|---|---|---|---|---|---|
| Copper IUD (Paragard) | 380 mm² copper device | Up to 120 hr (5 days) | Direct spermicide; sterile endometrial inflammation | Most effective (>99.9%); unaffected by body weight or BMI | Immediate Tier 1 contraception for up to 10–12 years. |
| 52 mg LNG-IUS (Mirena, Liletta) | 52 mg levonorgestrel system | Up to 120 hr (5 days) | Cervical mucus thickening; sterile endometrial inflammation | Non-inferior to Copper IUD; highly effective across all BMIs | Immediate Tier 1 contraception for up to 8 years. |
| Ulipristal Acetate (Ella) | 30 mg oral tablet | Up to 120 hr (5 days) | Selective progesterone receptor modulator (SPRM); delays follicular rupture even after LH surge starts | Superior efficacy in BMI ≥30 kg/m² vs levonorgestrel | Delay hormonal start ≥5 days; backup until 7 days after starting. |
| Oral Levonorgestrel (Plan B) | 1.5 mg oral tablet (or 0.75 mg q12h x 2) | Up to 72 hr (declines 72–120 hr) | High-dose progestin; blocks LH surge before it begins | May be less effective with BMI ≥30 kg/m²; still better than no EC (UPA or an IUD preferred) | Immediate "quick start" permitted; barrier backup for 7 days. |
| Yuzpe Regimen | Combined COCs: 100 mcg EE + 0.5 mg LNG q12h x 2 | Up to 72 hr | Suppresses LH surge; alters tubal motility | Lower efficacy (~75%); high nausea (50%) and emesis (20%) | Historical interest; premedicate with oral antiemetics. |
Post-EC Bridging Protocols
Ulipristal Acetate (UPA) Bridging Protocol
Ulipristal acetate is a selective progesterone receptor modulator (SPRM). If exogenous progestins (from pills, patches, rings, injections, or implants) are started immediately after UPA, competitive binding occurs: the progestin displaces UPA from receptors, neutralizing UPA's emergency contraceptive efficacy while impairing the progestin's contraceptive onset.
- The 5-Day Delay Rule: Patients must wait at least 5 full days after taking UPA before initiating or resuming any hormonal contraceptive method.
- Backup Contraception: The patient must abstain or strictly utilize barrier methods during the 5-day waiting period plus an additional 7 days of active hormonal contraception (about 12 days in total).
Oral Levonorgestrel Bridging Protocol
Levonorgestrel does not compete antagonistically. Patients can quick-start hormonal contraception immediately on the same day oral levonorgestrel is taken. A backup method is needed for 7 days (2 days for a norethindrone or norgestrel POP).
Barrier Methods of Contraception
Condoms & STI Protection
External (male) condoms (latex, polyurethane, polyisoprene) and internal (female) condoms (nitrile sheath with retention rings) are the only contraceptive methods providing substantial protection against Sexually Transmitted Infections (STIs), including HIV, gonorrhea, chlamydia, and trichomoniasis.
- Lubricant Compatibility: Latex condoms degrade rapidly when exposed to oil-based lubricants (petroleum jelly, baby oil, mineral oil, lotions), breaking down within 60 seconds. Only water-based or silicone lubricants are safe with latex. Polyurethane and polyisoprene condoms are safe with oil-based lubricants and in latex allergy.
Cervical Barriers: Diaphragms & Cervical Caps
- Diaphragms (Caya, Traditional Spring-Loaded): Silicone dome covering the ectocervix, anchored between the posterior fornix and pubic symphysis. Must be used with spermicidal gel. Must remain in place for at least 6 hours post-coitus (dwell time) to ensure sperm immobilization, but must be removed within 24 hours to prevent Toxic Shock Syndrome (TSS). Refitting is required following weight changes of ≥10–15 lbs, term delivery, or pelvic surgery.
- Cervical Cap (FemCap): Silicone cup fitting over the cervix via suction. Minimum dwell time is 6 hours; maximum wear time is 48 hours. Efficacy is significantly reduced in parous individuals.
Vaginal pH Modulator Gel (Phexxi)
- Lactic acid, citric acid, and potassium bitartrate gel inserted up to 1 hour before each act of intercourse; it keeps vaginal pH acidic so sperm lose motility. Typical-use failure is about 14% per year, it offers no STI protection, and it should be avoided in patients with recurrent urinary tract infections or urinary tract abnormalities (cystitis was a leading adverse event).
Spermicides & Nonoxynol-9 Toxicity
- Mechanism: Nonoxynol-9 (N-9) is a surfactant that disrupts sperm cell membranes. Typical failure rate is high (~21–28%).
- Mucosal Safety Warning: Nonoxynol-9 does not protect against STIs or HIV. Frequent use (multiple times daily) causes chemical disruption and micro-ulcerations of the vaginal and cervical epithelium. This disruption promotes inflammatory leukocyte recruitment, increasing the risk of HIV transmission. CDC and WHO guidelines strictly contraindicate N-9 use in individuals with, or at risk for, HIV/STIs.
Fertility Awareness-Based Methods (FABMs)
FABMs identify the fertile window based on gamete physiology: sperm survive up to 5 days in fertile cervical mucus, while the unfertilized ovum survives 12–24 hours post-ovulation (a 6-day fertile window).
- Lactational Amenorrhea Method (LAM): More than 98% effective while all three conditions hold: amenorrhea since delivery, fully or nearly fully breastfeeding (US MEC 2024: no more than 4 hours between feeds by day and 6 hours at night), and infant younger than 6 months.
- Standard Days Method (SDM / CycleBeads): Valid only for women with regular menstrual cycles between 26 and 32 days. Intercourse is avoided (or barrier methods used) on cycle days 8 through 19 inclusive.
- TwoDay Method: Based on daily evaluation of cervical secretions. The woman asks: (1) "Did I notice secretions today?" and (2) "Did I notice secretions yesterday?" If secretions are present on either today or yesterday, she is considered fertile. If no secretions are present on both days, pregnancy is unlikely.
- Billings Ovulation Method: Tracks vulvar sensation and cervical mucus. Rising follicular estradiol stimulates endocervical crypts to produce clear, stretchy, slippery, lubricative mucus (spinnbarkeit, raw egg white consistency). The "peak day" is the last day of slippery mucus; ovulation occurs within 48 hours of peak mucus. The infertile phase begins on the fourth evening after the peak day.
- Symptothermal Method: Combines cervical mucus observation with daily Basal Body Temperature (BBT) taken upon waking before activity. Following ovulation, progesterone secreted by the corpus luteum exerts a thermogenic action on the hypothalamus, causing a sustained thermal shift of 0.4°F to 1.0°F (0.2°C to 0.5°C). The post-ovulatory infertile phase begins on the evening of the third consecutive day of elevated temperatures above the preceding six baseline temperatures (the "3 over 6" rule).
A 25-year-old female presents to the clinic on Monday morning requesting emergency contraception after an episode of condom breakage that occurred on Friday night (approximately 60 hours ago). Her BMI is 32 kg/m². She desires oral emergency contraception and wants to know which oral regimen is most effective for her. Which evidence-based recommendation should the WHNP provide?
Oral levonorgestrel 1.5 mg in a single dose is preferred because its efficacy is unaffected by body weight or BMI up to 72 hours.
Oral ulipristal acetate 30 mg is preferred because it works up to 120 hours and is more effective than levonorgestrel at a BMI of 30 or higher.
The Yuzpe method using high-dose combined oral contraceptives should be initiated immediately because oral progestin-only emergency contraception is ineffective after 48 hours.
No oral emergency contraception will be effective at 60 hours post-coitus, making surgical termination the only medical alternative.
A 22-year-old female presents to the clinic 48 hours after unprotected intercourse and receives a prescription for ulipristal acetate (Ella, 30 mg) for emergency contraception. She also desires to start combined oral contraceptive pills (COCs) for ongoing pregnancy prevention. What is the correct protocol for initiating her combined oral contraceptive pills following ulipristal acetate administration?
Start the combined pill pack today ('quick start') with no backup barrier method required at any point.
Start the combined pill pack today and use a backup barrier method for the first 7 days of pill use.
Wait at least 5 days after ulipristal to start pills; use a barrier method or abstain until 7 days after the first pill.
Defer starting combined oral contraceptives for 3 months to avoid severe hepatic cytochrome P450 competitive inhibition.
A couple presents for family planning counseling. They wish to utilize a Fertility Awareness-Based Method (FABM) that incorporates both biological markers of ovulation and strict rules for identifying the post-ovulatory infertile phase. The WHNP explains the symptothermal method. What physiological event causes the post-ovulatory basal body temperature (BBT) elevation utilized in this method?
The mid-cycle surge of pituitary luteinizing hormone (LH) stimulating hypothalamic shivering reflexes.
The rapid peak of pre-ovulatory estradiol acting on the preoptic anterior hypothalamic thermoregulatory center.
Increased metabolic clearance of thyroid hormones triggered by follicular rupture.
Thermogenic action on the hypothalamus mediated by progesterone produced by the corpus luteum following ovulation.
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