I've recently come across a public access paper that does a great job of showing how important testosterone (and DHT) are for male development in primates. Better still, the full paper is available free on PMC:
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3146061/Effects of prenatal androgens on rhesus monkeys: A model system to explore the organizational hypothesis in primatesIt's a summary of the research that's been conducted over the years into the effects of prenatal hormone treatment with two androgenic hormones (testosterone and DHT) on Rhesus monkeys. Rhesus monkeys are genetically a lot closer to humans than most of the animals used in other such research, and they have a fairly similar pattern of gestation and prenatal development to us too. In other words, whatever applies to them probably applies to us as well.
In some of the experiments, the researchers appear to have been successful in producing genetically female monkeys who were physically fully male, just by dosing the mother with testosterone or DHT. In other experiments, they produced monkeys who appeared female, but whose behaviour (and response as adults to testosterone injections) was male. In other words, the researchers created FTM transgender monkeys, purely through administration of androgenic hormones at the appropriate time during pregnancy.
Reading through that paper makes it clear why giving a pregnant woman any of the following:
androgenic hormones;
antiandrogens;
drugs that interfere with testosterone production (such as DES or progestins),
creates an obvious risk of producing physical abnormalities of sexual development (and/or later problems with gender identity) in her unborn child.
I think the only reason this is in any way controversial is because millions of pregnant women have already been given drugs with these properties. The number of people who've already been affected must be very large, so large that it's impossible for anyone who knows about it to acknowledge what's happened. And so the disaster carries on, and more and more people like us continue to be born. Not that I see anything wrong with being trans, however it does tend to result in a very difficult life for those affected and those around them, so if there's an easy way to prevent it from happening in the first place by just discontinuing the use of certain medications, then obviously that's what should happen.
