Any advice about having children during grad school, from the perspective of (a) female grad students and (b) students without stay-at-home partners?

What you end up doing is going to be very specific to your individual circumstances, but I can give you my two cents about how my wife and I handled this situation. Currently, I'm a 4th year PhD student and my wife is 2 years into a MS degree with the aim to get a PhD. We both hope to stay in academia. We have two kids, ages 4 and 6 mo.

Our first kid came before either of us were in grad school, and our second came a year later than we had planned. Our decision was to have kids earlier rather than later because grad school is more flexible in terms of schedules than real jobs. This really helpful when my wife was practically bed-ridden for a couple months of her first trimester with our second kid.

We didn't want to stick our kids in daycare full time, and we have no family around to help, so we came up with a switch-off schedule. My wife works from 4am-noon (and some hours on weekends) and then we switch off and I work noon-6pm. Then I work at night from home after she goes to sleep (early). Our 4 year old does go to pre-school a few hours a week and the baby naps, so I can put in a few more hours during the day this way. Of course, schedules like this depend on our advisors being okay with our hours, and for our work (me CS, her biochemistry), it works out. Depending on where you are and at what point (and structure) of your MD-PhDs, you might be able to do this.

One consideration is that by the time both of us are on the job market for tenure-track positions, both kids will be school age, which allows us to both work normal business hours. Also, by the time I'm into a post-doc, our baby should be sleeping through the night. Until that happens, caring for children is very draining and it does affect my productivity in research.

As far as I know, my wife did not experience any overt discrimination against her for being pregnant. Her supervisor was generally supportive and understanding even when she couldn't work because she was too sick. However, as with many medical conditions (e.g. disability, known mental health issues), you're sure to encounter at least unconscious bias for being pregnant.

I will answer based on my experience and that of approx. 4 other women in my department who had kids (without stay-at-home spouses) during our PhD program.

For women who had kids while they were in graduate school -- how did you decide on when to have kids? Earlier in grad school vs. later?

There were a variety of approaches, but I think the key is to have children in a year where deadlines are flexible. So one of the students had a child very early (while taking classes) because there was no hard stop on when the classes had to be done by, and she could basically take a semester off from classes without real consequences. Three of us had children during the 3rd and 4th years when we were expected to work on our dissertations. Some were a bit ahead and didn't need to stretch the time to degree as a result of the pause, and some, like me, did. I think this was the best timing because we had a good foundation in the program/relationship with our advisors but were in a very flexible time period. I also had a fellowship for that year so it made funding easier. The person who had a child during the job market year had the hardest time, since those deadlines are non-negotiable.

Also, how did you approach being pregnant in an academic environment? (i.e. did anyone harass you as being 'less dedicated'?

I stressed a lot about this. My approach was to foreground my research and academic plans in all conversations, while backgrounding my pregnancy. I set meetings with my advisors to discuss the pregnancy and presented it as a scheduling challenge - I am going to have a period of decreased productivity because I am pregnant so here is my proposed plan to stay on track. Here is what you can expect from me in the next 6 months to get ahead as much as possible, etc. I found this worked really well. When people asked in the hall about how I was doing I gave them a positive research-related answer, not a pregnancy answer. The only person who gave a poor reaction was the Director of Graduate Studies, who assumed that the pregnancy meant I would be targeting lesser positions. I corrected him, of course. If he had any real sway over my life I would have made sure my committee knew about it and could discuss the issue with him. I think that others had a similar mix of reactions... mostly supportive with some "lesser expectations" attitudes that needed to be countered.

How did you deal with childcare?

With the exception of one person with nearby relatives, all of us paid for the best childcare we could afford (nanny or day care). You want peace of mind, trust, and communication--and that often means $$. We all made sure to set a consistent schedule (baby likes consistency). We differed in how soon we came back to work and how many hours per week we worked. That is a personal choice and based on your goals and work required to achieve those goals.