From the Guidelines
Plan B (levonorgestrel 1.5 mg) is considered safe for use in lactating women who need emergency contraception, as classified under category 1 by the U.S. Medical Eligibility Criteria for Contraceptive Use, 2010 1. The woman should take the single 1.5 mg dose as soon as possible within 72 hours after unprotected intercourse, though it may be effective up to 5 days. While using Plan B, breastfeeding can continue without interruption as the amount of hormone that passes into breast milk is very small and not harmful to the infant. The medication works primarily by preventing or delaying ovulation, and it will not affect milk production or quality. Some key points to consider include:
- Side effects may include irregular bleeding, nausea, headache, and breast tenderness, but these are typically mild and temporary.
- It's essential to note that Plan B is not intended for regular contraception and does not protect against sexually transmitted infections.
- If the woman experiences severe abdominal pain after taking Plan B, she should seek medical attention as this could indicate an ectopic pregnancy.
- For ongoing contraception while breastfeeding, progestin-only methods like the mini-pill, implant, or IUD are generally recommended options to discuss with a healthcare provider, and any regular contraceptive method can be started immediately after the use of levonorgestrel ECPs 1.
From the Research
Emergency Contraception for Lactating Women
- The use of levonorgestrel for emergency contraception in lactating women has been studied, with a focus on the pharmacokinetics of the drug in plasma and milk 2.
- A study found that the concentrations of levonorgestrel in milk were consistently lower than those in plasma, with a mean milk:plasma ratio of 0.28 2.
- The estimated infant exposure to levonorgestrel was found to be 1.6 microg on the day of dosing, 0.3 microg on the second day, and 0.2 microg on the third day 2.
- To limit infant exposure to the period of maximum levonorgestrel excretion in milk, mothers may need to discontinue nursing for at least 8 hours, but not more than 24 hours, after emergency contraception 2.
Dosage and Administration
- The American College of Obstetricians and Gynecologists recommends a single dose of levonorgestrel 1.5 mg for emergency contraception as one option 3.
- Another option is two doses of levonorgestrel 0.75 mg, which can be taken 12-24 hours apart 3, 4.
- A systematic review found that a single dose of levonorgestrel 1.5 mg is not inferior in efficacy to the two-dose regimen, and that all regimens studied were very efficacious for emergency contraception if taken within 72 hours of unprotected coitus 4.
Safety and Efficacy
- The safety and efficacy of levonorgestrel for emergency contraception have been established in several studies 3, 5, 4.
- The main side effect of levonorgestrel is frequent menstrual irregularities, and no serious adverse events have been reported 4.
- Levonorgestrel has been found to be effective in preventing pregnancy, with a success rate of around 80% 5.