If you’re weighing copper iud emergency contraception against a morning-after pill, breastfeeding usually does not mean you need to delay treatment or stop feeds. The copper IUD is the most effective option; levonorgestrel and ulipristal are pills with different time windows. For breastfeeding, current specialist guidance supports continuing feeds after a single dose of either pill, though information is more limited for ulipristal.
Copper IUD emergency contraception: the most effective option
A copper IUD (also called a copper coil) must be inserted by a trained clinician. It can be used within five days (120 hours) after unprotected sex, and in some circumstances a clinician may assess timing against ovulation as well. It does not contain hormones, so there is no medication entering breast milk. Breastfeeding does not need to pause because of the device.
It is also the most effective emergency method. A 2014 review by Kelly Cleland, Elizabeth Raymond, Elizabeth Westley and James Trussell summarized 42 studies and reported a pregnancy rate below 0.1% after copper IUD insertion for emergency contraception. The IUD can also provide ongoing contraception if you choose to leave it in. It requires an appointment and insertion, however, so access and timing may affect whether it is practical for you.
Levonorgestrel and ulipristal: act promptly
Levonorgestrel is sold under names including Plan B in the United States. Take it as soon as possible. The time limit differs by country and product guidance: Australian guidance allows use up to four days after sex, while local instructions elsewhere may set a shorter window. It is generally less effective later in the window, so contact a pharmacist or sexual-health service promptly if more than 72 hours have passed.
Ulipristal acetate is another emergency contraceptive pill and can be taken within five days. It is generally the more effective pill, especially later in that window. In the 2014 review, a meta-analysis of two comparison studies found lower odds of pregnancy with ulipristal than levonorgestrel when taken within 72 hours. These are comparisons between study groups, not a guarantee of what will happen for an individual.
The same review reported clinical-trial pregnancy rates of 0.9%–2.1% for ulipristal and 0.6%–3.1% for levonorgestrel. Those ranges come from different trials and overlap, so they should not be read as a direct head-to-head ranking. The copper IUD remains the most effective option overall; among pills, ulipristal is generally preferred when it is suitable and available.
Do you need to pause breastfeeding?
For a single dose of levonorgestrel, specialist UK medicines guidance says you can continue breastfeeding; routine expressing and discarding of milk is not needed. The same guidance supports continuing feeds after a single dose of ulipristal, although breastfeeding data for ulipristal are more limited than for levonorgestrel. Local product leaflets and advice can differ, particularly for ulipristal, so check with a pharmacist or clinician if the instructions you receive say to pause feeds.
A copper IUD does not require a breastfeeding break. If a pill is the option you can access fastest, do not postpone asking about it while trying to arrange an IUD. Tell the pharmacist or clinician that you are breastfeeding and when the unprotected sex occurred; that helps them discuss suitable options and local guidance.
What to consider next
Emergency contraception does not protect you from sex later in the same cycle. Ask when to start or restart your regular contraception, since the timing differs after ulipristal and levonorgestrel. You can read more about when to restart birth control after ulipristal.
If your next period is more than seven days late, or is unusually light, take a pregnancy test. Breastfeeding can make periods irregular or absent, so if you are unsure when to test, ask a healthcare professional. A pharmacist, sexual-health clinic or clinician can help you choose based on elapsed time, availability, medicines you take and your plans for ongoing contraception.