A nationwide drop in the number of genital warts cases has been attributed to the controversial HPV vaccine, which is free for teenage girls.
Sexual health clinics reported a 10% decrease in genital warts last year compared to 2010, according to the Institute of Environmental Science and Research's annual report on sexually transmitted infections.
Family Planning national medical advisor Christine Roke attributed the fewer first-time cases of genital warts to the HPV vaccine, which was introduced in late 2008.
"It reduces the chances of getting warts if people have [the vaccine] before they are sexually active."
The vaccine - now a routine immunisation for 12-year-old girls - aims to protect women against human papillomavirus and the risk of developing cervical cancer later in life.
About 150 women are diagnosed with cervical cancer and 60 women die from it each year in New Zealand.
The ESR report also showed a nationwide decrease in gonorrhoea and syphilis.
Nationally, rates of chlamydia have remained steady since 2008, but it is still the most common STI with 25,666 cases reported last year. If left untreated, the infection can damage a woman's reproductive organs.
Similar to 2010 figures, there were 105 cases of infants having chlamydia and two with gonorrhoea - transmitted from their mother at birth, Dr Roke said.
"If the mother either hasn't been tested at all or they've caught the infection again since they were tested in the pregnancy and they're carrying [it] the mum might not know, but as the baby is born through the genital tract for gonorrhoea it's mainly in the eye, for chlamydia it's mainly in the eye and the lungs that the baby can get the infection."
Chlamydia in infants can be life-threatening if it spreads to the lungs and causes pneumonia.
Left untreated, eye infections from both can lead to blindness.
The decrease in gonorrhoea suggests people are being "a bit more careful with safer sex practices", Dr Roke said.
"It's wonderful that [gonorrhoea] rates are dropping down because that's probably the best indicator for safer sex."
The most outstanding STI statistic in the country was gonorrhoea within the Tairawhiti District Health Board, covering Gisborne and the East Coast. ESR found the region reported the highest gonorrhoea rate per population - over five times the estimated national rate.
STIs are not notifiable in New Zealand and the surveillance system relies on the ongoing support of clinic and laboratory staff.
The report is based on data collected from several sources such as sexual health clinics, family planning clinics, student and youth health clinics and laboratories.