Kiwi men are doing their bit for family planning, with an increasing percentage having "the snip", while fewer women are having their tubes tied, a new study indicates.

Among women aged 35 to 54, the proportion citing ever having relied on male vasectomy has increased sharply, to 40 per cent, from 26 per cent in the mid-1980s.

The proportion who have had tubal ligation fell to 8 per cent, from 22 per cent.

"From the findings of the current study, the prevalence of use of permanent methods of contraception (vasectomy and tubal ligation) in New Zealand has not changed in the last 30 years," the Canterbury and Otago University researchers say in The New Zealand Medical Journal.


"What has changed is a couple's choice of sterilisation procedure, such that with the fall in the prevalence of tubal ligation there is a compensatory rise in the prevalence of ever-use of vasectomy.

"The shift to vasectomy may be due to ease of performing the procedure, lower risk of complications and change in men's attitude towards sterilisation."

However the true rate of vasectomy may have been under-reported in the survey, which relied on women's knowledge and recall regarding their male sexual partners' having had the snip.

A study in the late 1990s found that 44 per cent of men aged 40 to 74 had had a vasectomy.

The new study found ever-use of oral contraceptive pills rose from 75 per cent of women, to 89 per cent. Contraceptive injections rose from 10 to 15 per cent; intrauterine devices from 17 to 20 per cent; and condoms from 24 to 64 per cent.

The great increase in the use of condoms may be related to sexual transmitted infections.

"With the advent of HIV/AIDS, public education has promoted the use of condoms as a way of reducing the risk of sexually transmitted infections," the journal paper states.

The researchers say New Zealand has a high prevalence of vasectomy and ever-use of the pill compared with other countries. They cite a 2003 study of several European countries in which 85 per cent of women aged 15 to 49 had used oral contraceptives and 11 per cent used sterilisation methods, both male and female sterilisation.

Auckland women's health advocate Lynda Williams said, "I think women know and so do men that a vasectomy is much quicker procedure and easier to recover from than a tubal ligation.

"I think more women now are prepared to discuss vasectomy with their partners than probably was the case in the 80s.

"I do see that there is a greater acceptance of vasectomy amongst the male population."