1.   Can women who could get sexually transmitted infections (STIs) use progestin-only injectables?

Yes. Women at risk for STIs can use progestin-only injectables. The few studies available have found that women using DMPA were more likely to acquire chlamydia than women not using hormonal contraception. The reason for this difference is not known. There are few studies available on use of NET-EN and STIs. Like anyone else at risk for STIs, a user of progestin-only injectables who may be at risk for STIs should be advised to use condoms correctly every time she has sex. Consistent and correct condom use will reduce her risk of becoming infected with an STI.

2. Can women at high risk for HIV use progestin-only injectables?

Yes. Women at high risk of HIV infection can use any contraceptive method, including progestin-only injectables, except spermicide or diaphragm with spermicide (see Spermicides and Diaphragms).

In late 2016 a WHO assessment observed that some research finds that women who are at high risk of HIV infection and use a progestin-only injectable are slightly more likely to get HIV. It is not clear why studies find this. The injectable may or may not be responsible for increasing a woman’s chances of becoming infected if exposed to HIV.

An expert group convened by WHO concluded, “Women should not be denied the use of progestogen-only injectables because of concerns about the possible increased risk” of HIV infection. WHO classified progestin-only injectables, such as DMPA (including Sayana Press) and NET-EN, as Medical Eligibility Criteria (MEC) category 2 for high risk of HIV. This classification means that women at high risk of HIV can generally use the method.

WHO advises that, in countries and populations where HIV is common, providers should clearly inform women interested in progestin-only injectables about these research findings and their uncertainty, as well as how to protect themselves from HIV, so that each woman can make a fully informed choice (see Considering Progestin-Only Injectables Where HIV Risk Is High for counseling tips). In keeping with the MEC 2 Classification, women should be told clearly that they can choose and use a progestin-only injectable if they wish. Women also should be told that other long-acting and effective methods are available if they would like to consider a different method.

3.   If a woman does not have monthly bleeding while using progestin-only injectables, does this mean that she is pregnant?

Probably not, especially if she is breastfeeding. Eventually most women using progestin-only injectables will not have monthly bleeding. If she has been getting her injections on time, she is probably not pregnant and can keep using injectables. If she is still worried after being reassured, she can be offered a pregnancy test, if available, or referred for one. If not having monthly bleeding bothers her, switching to another method may help.

4.   Can a woman who is breastfeeding safely use progestin-only injectables?

Yes. This is a good choice for a breastfeeding mother who wants a hormonal method. Progestin-only injectables are safe for both the mother and the baby starting as early as 6 weeks after childbirth. They do not affect milk production.

5.   How much weight do women gain when they use progestin-only injectables?

Women gain an average of 1–2 kg per year when using DMPA. Some of the weight increase may be the usual weight gain as people age. Some women, particularly overweight adolescents, have gained much more than 1–2 kg per year. At the same time, some users of progestin-only injectables lose weight or have no significant change in weight. Asian women in particular do not tend to gain weight when using DMPA.

6.   Do DMPA and NET-EN cause abortion?

No. Research on progestin-only injectables finds that they do not disrupt an existing pregnancy. They should not be used to try to cause an abortion. They will not do so.

7.   Do progestin-only injectables make a woman infertile?

No. There may be a delay in regaining fertility after stopping progestin-only injectables, but in time the woman will be able to become pregnant as before, although fertility decreases as women get older. The bleeding pattern a woman had before she used progestin-only injectables generally returns several months after the last injection even if she had no monthly bleeding while using injectables. 

8.   How long does it take to become pregnant after stopping DMPA or NET-EN?

Women who stop using DMPA wait about 4 months longer on average to become pregnant than women who have used other methods. This means they become pregnant on average 10 months after their last injection. Women who stop using NET-EN wait about one month longer on average to become pregnant than women who have used other methods, or 6 months after their last injection. These are averages. A woman should not be worried if she has not become pregnant even as much as 12 months after stopping use. The length of time a woman has used injectables makes no difference to how quickly she becomes pregnant once she stops having injections.

After stopping progestin-only injectables, a woman may ovulate before her monthly bleeding returns—and thus can become pregnant. If she wants to continue avoiding pregnancy, she should start another method before monthly bleeding returns.

9.   Does DMPA cause cancer?

Many studies show that DMPA does not cause cancer. DMPA use helps protect against cancer of the lining of the uterus (endometrial cancer). Findings of the few studies on DMPA use and breast cancer are similar to findings with combined oral contraceptives: Women using DMPA were slightly more likely to be diagnosed with breast cancer while using DMPA or within 10 years after they stopped. It is unclear whether these findings are explained by earlier detection of existing breast cancers among DMPA users or by a biologic effect of DMPA on breast cancer.

A few studies on DMPA use and cervical cancer suggest that there may be a slightly increased risk of cervical cancer among women using DMPA for 5 years or more. Cervical cancer cannot develop because of DMPA alone, however. It is caused by persistent infection with human papillomavirus (see What Is Cervical Cancer?). Little information is available about NET-EN. It is expected to be as safe as DMPA and other contraceptive methods containing only a progestin, such as progestin-only pills and implants.

10.   Can a woman switch from one progestin-only injectable to another?

Switching injectables is safe, and it does not decrease effectiveness. If switching is necessary due to shortages of supplies, the first injection of the new injectable should be given when the next injection of the old formulation would have been given. Clients need to be told that they are switching, the name of the new injectable, and its injection schedule.

11.  How does DMPA affect bone density?

During use, DMPA decreases bone mineral density slightly. This may increase the risk of developing osteoporosis and possibly having bone fractures later, after menopause. WHO has concluded that this decrease in bone mineral density does not place age or time limits on use of DMPA.

12.  Do progestin-only injectables cause birth defects? Will the fetus be harmed if a woman accidentally uses progestin-only injectables while she is pregnant?

No. Good evidence shows that progestin-only injectables will not cause birth defects and will not otherwise harm the fetus if a woman becomes pregnant while using progestin-only injectables or accidentally starts injectables when she is already pregnant.

13.  Do progestin-only injectables lower women’s mood or sex drive?

Generally, no. Some women using injectables report these complaints. The great majority of injectables users do not report any such changes, however. It is difficult to tell whether such changes are due to progestin-only injectables or to other reasons. Providers can help a client with these problems (see Mood changes or changes in sex drive). There is no evidence that progestin-only injectables affect women’s sexual behavior.

14.  What if a woman returns for her next injection late?

A woman can have her next DMPA injection even if she is up to 4 weeks late, without the need for further evidence that she is not pregnant. A woman can receive her next NET-EN injection if she is up to 2 weeks late. Some women return even later for their repeat injection, however. In such cases providers can use the instructions in Ruling Out Pregnancy. Whether a woman is late for reinjection or not, her next injection of DMPA should be planned for 3 months later, or her next injection of NET-EN should be planned for 2 months later, as usual.