When to Start

IMPORTANT: A woman can start injectables any time she wants if it is reasonably certain she is not pregnant. To be reasonably certain she is not pregnant, use the Pregnancy Checklist.

Woman's situation When to start
Having menstrual cycles or switching from a nonhormonal method

Any time of the month

  • If she is starting within 7 days after the start of her monthly bleeding, no need for a backup method.
  • If it is more than 7 days after the start of her monthly bleeding, she can start injectables any time if it is reasonably certain she is not pregnant. She will need a backup method* for the first 7 days after the injection.
  • If she is switching from an IUD, she can start injectables immediately (see Copper-Bearing IUD, Switching From an IUD to Another Method).
Switching from a hormonal method
  • Immediately, if she has been using the hormonal method consistently and correctly or if it is otherwise reasonably certain she is not pregnant. No need to wait for her next monthly bleeding. No need for a backup method.
  • If she is switching from another injectable, she can have the new injectable when the repeat injection would have been given. No need for a backup method.
Fully or nearly fully breastfeeding

Less than 6 months after giving birth

  • Delay her first injection until 6 months after giving birth or when breast milk is no longer the baby's main food—whichever comes first.
More than 6 months after giving birth
  • If her monthly bleeding has not returned, she can start injectables any time if it is reasonably certain she is not pregnant. She will need a backup method for the first 7 days after the injection.
  • If her monthly bleeding has returned, she can start injectables as advised for women having menstrual cycles.
Partially breastfeeding

Less than 6 weeks after giving birth

  • Delay her first injection until at least 6 weeks after giving birth.
More than 6 weeks after giving birth
  • If her monthly bleeding has not returned, she can start injectables any time if it is reasonably certain she is not pregnant. She will need a backup method for the first 7 days after the injection.
  • If her monthly bleeding has returned, she can start injectables as advised for women having menstrual cycles.
Not breastfeeding

Less than 4 weeks after giving birth

  • She can start injectables at any time on days 21–28 after giving birth. No need for a backup method. (If additional risk for VTE, wait until 6 weeks. See Question 2.)
More than 4 weeks after giving birth
  • If her monthly bleeding has not returned, she can start injectables any time if it is reasonably certain she is not pregnant. She will need a backup method for the first 7 days after the injection.
  • If her monthly bleeding has returned, she can start injectables as advised for women having menstrual cycles.
No monthly bleeding (not related to childbirth or breastfeeding)
  • She can start injectables any time if it is reasonably certain she is not pregnant. She will need a backup method for the first 7 days after the injection.
After miscarriage or abortion
  • Immediately. If she is starting within 7 days after first- or second-trimester miscarriage or abortion, no need for a backup method.
  • If it is more than 7 days after first- or second-trimester miscarriage or abortion, she can start injectables any time if it is reasonably certain she is not pregnant. She will need a backup method for the first 7 days after the injection.
After taking emergency contraceptive pills (ECPs)

After taking progestin-only or combined ECPs:

  • She can start or restart injectables on the same day as taking the ECPs. There is no need to wait for her next monthly bleeding to have the injection.
  • She will need to use a backup method for the first 7 days after the injection. 
  • If she does not start immediately, but returns for injectables, she can start  at any time if it is reasonably certain she is not pregnant.

After taking ulipristal acetate (UPA) ECPs:

  • She can start or restart injectables on the 6th day after taking UPA-ECPs. No need to wait for her next monthly bleeding. Monthly injectables and UPA interact. If an injectable is started sooner, and thus both are present in the body, one or both may be less effective.
  • Make an appointment for her to return for the injection on the 6th day after taking UPA-ECPs, or as soon as possible after that. 
  • She will need to use a backup method from the time she takes UPA-ECPs until 7 days after the injection.
  • If she does not start on the 6th day but returns later for injectables, she may start at any time if it is reasonably certain she is not pregnant.

* Backup methods include abstinence, male and female condoms, spermicides, and withdrawal. Tell her that spermicides and withdrawal are the least effective contraceptive methods. If possible, give her condoms.

Where a visit 6 weeks after childbirth is routinely recommended and other opportunities to obtain contraception limited, some providers and programs may give the first injection at the 6-week visit, without further evidence that the woman is not pregnant, if her monthly bleeding has not yet returned.