A drug prescribed to up to 2000 pregnant New Zealand women in the 1960s may be responsible for high rates of cancer and infertility among the next generation, a specialist says.
A court battle is under way in the United States led by 53 women who were exposed to a synthetic oestrogen called diethylstilbestrol (DES) while in the womb.
The women, all aged over 40, are suing drug companies who made and promoted the drug, using evidence from a 2011 study showing exposure via their pregnant mothers almost doubled their risk of developing breast cancer.
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The action is the first major litigation by so-called "DES daughters" that alleges a breast cancer link.
Otago University's Professor Charlotte Paul, who has researched the use of DES in New Zealand, says at least 600 and as many as 2000 women were given the hormone in a drug called Stilboestrol, which was thought to manage pregnancy symptoms.
The product was discontinued in 1971.
Prof Paul, a specialist in preventive and social medicine, says as well as breast cancer, DES daughters were known to have an increased risk of a rare cancer of the vagina called clear cell adenocarcinoma (CCA), and reproductive abnormalities.
Sons may also have some fertility problems. The mothers themselves have higher breast cancer rates.
Prof Paul says during the 1980s she tried to publish research on the problem but her paper was rejected by three journals.
"We got the sense that publicity ... was not actively sought - indeed the opposite - by doctors," she said.
During the 1990s, the Department of Health issued a pamphlet on the issue, however a DES register has never been set up and most health records from the time have since been destroyed, leaving the total number affected a mystery.
"It is a guess now," Prof Paul said.
The Boston-based court case is expected to run for several weeks.