This is a (really long) spinoff from another post (about whether waterbaby27 should have a baby in med school). People are always trying to figure out if they should have a baby at X point in their medical career, and people always respond with their stories, pro and con (including residentmom, who has had a baby in every point in her medical career!). That is great, since people need to know what kinds of situations can come up. But I was thinking about something more objective, like some kind of scored quiz where people could answer questions about their own situation and get an answer, like "this will probably work out well," or "this will be a total disaster," or "this has a 50% chance of working out." People who have already taken the plunge and had a child could see if the results reflect the reality of how difficult or easy it is.
So I have been thinking about making such a quiz, but I have no time, so I can't do it.

But what I have done is to list some things that seem like good predictors of how things will work out. By "work out" I mean that you will be able to continue your medical career and feel okay about the balance of family and work. Maybe this will be helpful. Maybe other people will add to the list, too.
Husband
It seems like the people with stay-at-home-dad husbands are usually very happy with that arrangement. Other good factors would be a husband who is willing to share child rearing and housework, a husband with a very flexible job, a husband who will not require you to move for him, a husband who would be willing to move for you, and a husband who values your medical career. Negative factors would be a husband in the military, a husband who is a surgeon, a husband who expects you to support his high-powered career, a husband who is not a good father or husband, and an absent husband (or no husband at all).
Family caregivers
It seems like the people whose parents or in-laws can provide a lot of free childcare are extremely grateful for that support. The number of family caregivers, their proximity, and their availability seem to be positive factors. Negative factors are family members who require your care, such as sick or elderly parents, or family members who would not do a good job for whatever reason.
Paid childcare
It is a big challenge to find childcare that is excellent, affordable, available at odd hours, and available for sick children. I don't know much about this part, but people have reported all kinds of good combinations of daycare, in-home caregivers, and caregivers on call. It seems like the wider your net of potential caregivers, the better.
Money
The more money you have, the more options you will have. It is expensive to raise a child, and it is also expensive to become a doctor. Husbands with money are also good, unless they are completely unavailable because of their high-powered work. Being willing to live frugally is a big plus.
Your attitude toward parenting and homemaking
A positive factor seems to be a willingness to delegate a lot of the parenting and homemaking. Negative factors seem to be the belief that mothers should stay home with young children or a lot of family pressure to do so (not that this is a negative or incorrect attitude, just that it makes it harder to balance motherhood and work because of the guilt).
Your attitude toward your medical career
Positive factors are a love for medicine, and a belief that you are/will be a good doctor despite not spending 100% of your time on medicine. A negative factor would be that your medical career is so important to you that you do not want anything to interfere with it (because having a child will definitely interfere), or conversely that your career is not as important as your husband's career (because then you are more likely to sacrifice your career). Feeling beaten down and disillusioned by the reality of medicine is another negative factor.
Your stage in education/training/practice
There are endless permutations on this one. So much depends on your local situation, such as a medical school with course material available in a variety of formats, or a culture of family-friendliness in your particular hospital. Then you have to think ahead to how old your child will be when you are an intern, etc. The only thing that seems clear to me is that internship is the worst time to have a baby.
Family-friendly field
To me, this means 2 things. First, how competitive is the field you want to enter? If you want to go into something super competitive, you will need to work very hard and do very well in medical school, and having a baby then could definitely hurt your chances. Second, once you get in, how flexible and supportive will your bosses and colleagues be? The availability of true part-time work, hours that correspond with daycare/school hours, and the ability to take time off (short- or long-term) are also positive factors. And just in case anybody did not know, surgery is not a family-friendly field.
Other commitments
Anything else that takes up your time will make it difficult to balance medicine and motherhood. Caring for an elderly or sick parent, other children to take care of, a long commute, a time-consuming hobby, or even a well-rounded life could be seen as negative factors if you are really pressed for time. On the other hand, already having other children can be a good thing if you already have a system of support that works well.
Unknown factors
You can't predict some things, such as infertility (although your age is an important predictor), complications of pregnancy and childbirth, a sick or special-needs child, an illness in you or your caregivers, or the collapse of medicine as we know it, but these things can definitely upset the balance of your life. And as they say, you can never really know what it is like to be a parent until you are one.
Your own influence on the above factors
You can influence a lot of these factors yourself, such as convincing your husband not to be a surgeon. You can plan ahead so that things are more likely to work out, such as picking a city for residency that is close to family members who can provide childcare.
So do these factors make sense to those who are parents? Did I leave out any major categories? Does anyone have anything to add? Does anyone want to create a scoring system for fun (SAHD husband = 10 points, surgeon husband = -10 points, etc.)? Sorry for the long post, but I just felt like putting it all out there in one place.