Teachers have very, very predictable schedules compared to practically everyone else. They're part of a reliable industry. They have a very clear career progression ahead of them. They have holidays, maternity leave, etc. It's very conducive to marriage and raising kids.

There are two things to consider from that.

1: people who want a stable married-with-kids life are likely to also want a stable, predictable career

2: People who happen to be in a stable, predictable career find it easier to say yes to marriage and kids

Teaching as a career gets a lot of flak for being underpaid, but in many cases it's actually paid pretty well on top of having solid retirement benefits, an incredible schedule, and a lot of stability. The pay, if it's low, is also not as much of an issue if the other partner makes a large amount of money, as is often the case right now for software developers. It can be an incredibly family friendly career.

My SO is going into teaching, at least temporarily for a few years, in a medium-COL city. She'll be making $55k-$65k in base salary, depending on if she teaches 10 months or 12 months out of the year, plus full retirement benefits, and they also provided her with enough scholarships just for taking the job that she has no college debt at all. Meanwhile I know engineering graduates (not necessarily software) who started in roughly the same range, with considerable debt, not as much stability, no retirement beyond a 401(k) with a pitiful match, and just a week or two off per year.

I think it's a familiarity bias with the occupation. More women have business degrees than nursing or education [1], but it may not seem so since business degree holders are more dispersed among types of businesses. The link seems to indicate that software developers are just as likely to marry accountants or nurses as teachers.

[1] http://www.collegeatlas.org/top-degrees-by-gender.html