Fifty percent of women and 53 percent of men, respectively, are trying to build a financial foundation before they have to support children.

But not all the postponement is so altruistic; the second most popular answer, given by 28 percent of women and 33 percent of men, is the desire to become more established and get ahead in their career.

Fifteen percent of women who plan to have children say they're waiting until at least age 35 to start a family. Sixty-three percent are waiting until at least age 30. Men are twice as likely to postpone having children until at least age 35, at 30 percent, and are equally likely as women to wait until at least until age 30, at 64 percent.

Salary level plays a big role in when they choose to begin a family, too, and usually women are way behind men in the levels of salary they consider acceptable for a family starting point.

Sadly, not just those salary levels but their expectations of how much they can earn during their careers—and at which point in their careers they'll earn it—are considerably lower than men's expectations.

And that can affect not just when they start families, but whether—and when—they might be able to retire.

Although postponing parenthood to build a career can give them more uninterrupted time in the workplace, and thus higher salaries and the opportunity to save more for retirement, the numbers are by no means encouraging that those delays will pay off when women are old enough to retire.

For instance, the report says that men are much more likely, at 44 percent, to estimate the salary they would ultimately reach in their careers at $100,000 or more, while just 20 percent of women expect to hit six figures.

Men's highest salary estimate is approximately $137,000, while women are expecting an average of just $79,000.

And men are aiming higher in job levels, too, with more than twice as many men expecting to hit levels of vice president (5 percent) and even company owner (9 percent) compared with women (2 percent and 4 percent, respectively).

Women, on the other hand, are more than twice as likely to expect to reach or remain at entry-level jobs, at 22 percent, compared with just 10 percent of men.

How much women might be able to save toward retirement in a career-long entry level/administrative/clerical job is dubious—particularly since many jobs at this level may not even offer the option to participate in a retirement plan.

Even if they do, lower salary levels will reduce the amount women can manage to save, and any matching employer funds will be correspondingly lower in amount than for their higher-paid colleagues—all leading to lower retirement balances when the time comes.

In addition, with 22 percent of women expecting to remain at that level even at the height of their careers, it's definitely not an encouraging picture for their eventual ability to retire.

That's probably why 18 percent of women are aiming to start a family when they've hit a salary range of $35,000–$49,999, compared with just 15 percent of men.

Men are aiming higher, with 34 percent postponing fatherhood until they hit a salary range of $50,000–$74,999, compared with just 25 percent of women.

But women appear to be basing their expectations on the realities of the job market, considering the continuation of the gender gap not only in pay but in advancement.

Thirty-four percent of women overall do not believe they earn the same pay as men with the same qualifications and experience—although 82 percent of men overall don't believe in the wage gap and say women make the same as they do.

While their evaluation of the wage gap varies depending on the industry in which they work—72 percent of women in health care say they believe they're being paid equally with male colleagues—44 percent of women in manufacturing say they're underpaid compared to the men.

And 77 percent of men in manufacturing say there is no wage gap—the biggest disconnect within a particular field between men and women on whether there is equal pay.