It's always a touchy subject - assume a woman is pregnant and you could be in for some harsh responses that will make you want to hide in a corner and cry. Pregnancy is a subject that needs to be approached gently and with the right techniques. Here are a few tips that will help you ask a woman if she is pregnant without having to duck her blows afterwards.
Try to avoid directly asking. Let's just state this right away - you really should never ask a woman if she is pregnant, even if it seems like she's ready to burst. This is because women come in all shapes and sizes and to assume that a woman is pregnant just because her belly is a bit rotund will only get you in trouble. Maybe she was pregnant and she just miscarried. Maybe she just delivered and her remaining weight is a touchy subject. Either way, you don't want to be caught in the midst of an emotional response to your naïve question. Never directly ask the question, "When are you due?" or "Are you expecting?". Period. There are others ways to find out if a woman is pregnant that won't leave you with your foot in your mouth.
Hint at what she'd like to drink. If you really want to find out if a woman is pregnant, eat dinner with her. See what she chooses to drink and let this help you build clues as to her pregnancy status. If she opts for something alcoholic, chances are she's just got a bit of a belly on her. If she opts for water and juice and turns down the free bottle of wine, there's a good chance that she's with child. But, you still shouldn't say anything. Keep looking for other clues to prove or disprove your theories.
Bring up the topic of children. If you want to know if a woman is pregnant, you can discuss the topic with her instead of outright asking her. Talk about your kids and casually question how many kids she wants to have. This might just lead her to start talking about her pregnancy. On the other hand, it might lead her to laugh in your face and deny the possibility of ever conceiving. Either way, talking about children should help you determine whether or not a woman is pregnant.
Mention your experience having children. If you can, also bring up your specific experiences related to childbirth. Talk about your own or your wife's pregnancy symptoms. If she can relate to you or she starts to joke with you about morning sickness and her recent distaste for all things spicy, you may just be on to something. On the other hand, if she says "I wouldn't know," and quickly dismisses the topic, she's probably not expecting. The important point is that you can't push a pregnant woman to tell you she's expecting. Get her to share the news when she's good and ready, and don't ask about it until she says those exact words.
Go clothes shopping with her. If you're up for some shopping, you can quickly find out if a woman is pregnant without having to ask her by shopping for clothes with her. Pregnant women have to buy specific maternity clothes. You'll soon find out her clothing needs if you venture to the mall with her. This should help you determine whether or not a woman is pregnant.