Contraceptive injections may be administered for January and March. Contraceptive injections have different effective times depending on the composition of the different drugs, so you can consult your doctor for details. Contraceptive injection is a kind of long-acting contraceptive measures, its composition is simple progestin, estrogen-progestin composite hormone. Its role is to be able to inhibit ovulation, change the viscosity of the endometrium and cervical mucus, reduce the chances of fertilization of the egg to bed, increase the success rate of contraception. The estrogen-progestin combination contraceptive injection is usually administered for 1 month, while the progestin-only contraceptive injection is usually administered for 3 months. After injection, the drug is stored locally and released slowly, which can play a long-lasting contraceptive effect. Although the effect of contraceptive injection is considerable, but there are some side effects, may lead to amenorrhea, menstrual disorders, obesity and so on. Currently, there are other contraceptive methods such as intrauterine devices and condoms, which can also be effective. Women who wish to use contraceptive injections for contraception are advised to use them under the guidance of a doctor and consult him/her for specific precautions.