My feelings might be influenced by the fact that I hardly drank pre-pregnancy. I also don't drive (which other people seem to think is a waste of a practical tee-totaller
) so my DH didn't have a lot of drinking opportunities anyway.
I think whether you are being unreasonable depends on the circumstances. If you used to go out and drink together and now he's going out alone to drink, leaving you at home then you will understandably feel abandoned and be concerned that he intends to do this throughout pregnancy and once the baby is born - leaving you holding the baby.
It might not be reasonable to ask him to abstain from alcohol altogether, but reminding him that you still want his company, but going out to pubs/bars etc where the main activity is drinking isn't fun for you anymore, and can he make sure that he sees this 9 months as a great opportunity to spend quality time as a couple before a baby becomes the centre of attention. (As opposed to seeing it as a great opportunity to spend quality time with alcohol
).
Life is changing for both of you, its pretty insensitive for him to carry on 'business as usual' just because you happen to be the one carrying the baby. This child is the responsibility of you both.
Find other things to do that you both enjoy, go see a movie (or watch one at home), go out for a meal, visit some place nice etc.
That said, I wouldn't stop him from drinking with a meal, or of an evening while you are having something non-alcoholic, as long as its more about spending time together rather than him getting drunk (whilst you can't) IYSWIM.
If you not drinking means that he's drinking more because you are a pre-ordained designated driver, then I can see that it would grate.
As an almost-non-drinker, I don't have a problem with other people drinking in social situations, like with a meal or whilst having a chat/doing something together. But I find situations where the main focus is alcohol difficult (like in pubs where it is too noisey to hold a conversation). That said, on a girls night out/in, I am just a giggly and enjoying things as those who have had alcohol so you don't need it as long as the company is fun.
I am a cheap date
In short, although it might be unreasonable to expect him to abstain for 9 months, it is reasonable to remind him that he has to consider your enjoyment of an evening too. As a pregnant woman you may have an aversion to the smell of alcohol, and you may (or may not!) be needing to feel close to your partner, so needing him to spend more non-drinking time with you.
Of course, if its simple jealousy then you are being unreasonable, but you're pregnant so its to be expected. 