Once every three months, women in the age group of 18-45 years will be given contraceptive injections free of cost at all state-run primary health centres and hospitals, state health minister C Vijaya Baskar said, launching the centrally-funded 'Antara' scheme at the Egmore Women and Children hospital on Thursday.The depot medroxyprogesterone acetate (DMPA) injection -added to the present basket of options such as condoms, intra-uterine devices, oral pills, morning-after pills and sterilisation procedures for men and women -contains the birth control hormone progestogen and is promoted as a safe option for women. It will be administered by doctors and staff nurses at government hospitals nearly four times a year to women who want to delay or avoid pregnancies.The injection is a safe and effective means of birth control for three months, said state family welfare director K Jyothi. "It offers an additional four week grace period before which the woman has to take the next shot. If the woman does not want to continue, she can get pregnant in four to six months." It gives women who are not able to convince their partners to use contraceptives another option.Gynaecologists say it is ideal for women who tend to skip oral pills every day . It does not interfere with sex or breast-feeding and helps women overcome problems of irregular, heavy or painful periods. It also reduces risk of ovarian or uterine cancer. "It is extremely good for a mass contraceptive programme," said senior gynaecologist Dr Jayashree Gajaraj.Like any other medication, this contraceptive has its limitations and side effects. While it can't be given to women with heart diseases, side-effects such as irregular bleeding will last for more than three months. "It is best to discuss options with the health care provider before using injectable or any other contraception," Dr Gajaraj said.