How Marriage and Motherhood Contribute to the Gender Wage Gap

Research from Sociologists and Economists Sheds Light

A business woman who is also a mother is all but guaranteed to suffer a motherhood penalty in terms of earnings.
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The gender wage gap is well-established in societies around the world. Social scientists have documented through research spanning decades that the gender wage gap—wherein women, all else being equal, earn less than men for the same work—cannot be explained away by differences in education, type of job or role within an organization, or by the number of hours worked in a week or weeks worked in a year.

Pew Research Center reports that in 2015—the year for which most recent data are available—the gender wage gap in the United States as measured by median hourly earnings of both full- and part-time workers was 17 percent. This means that women earned roughly 83 cents to the man's dollar.

This is actually good news, in terms of historical trends, because it means that the gap has shrunk considerably over time. Back in 1979, women earned just 61 cents to the man's dollar in terms of median weekly earnings, according to data from the Bureau of Labor Statistics (BLS) reported by sociologist Michelle J. Budig. Yet, social scientists are cautious about this overall improvement because the rate at which the gap is shrinking has declined significantly in recent years.

The encouraging nature of the overall shrinking gender wage gap also eclipses the continuing harmful effect of racism on a person's earnings.

When Pew Research Center looked at historical trends by race and gender, they found that, in 2015, while white women earned 82 cents to the white man's dollar, Black women earned just 65 cents relative to white men, and Hispanic women, just 58. These data also show that the increase in earnings of Black and Hispanic women relative to white men has been far less than that for white women.

Between 1980 and 2015, the gap for Black women shrunk by just 9 percentage points and that for Hispanic women by just 5. Meanwhile, the gap for white women shrunk by 22 points. This means that the closing of the gender wage gap over recent decades has primarily benefitted white women.

There are other "hidden" but important aspects of the gender wage gap. Research shows that the gap is tiny to non-existent when people start their working careers around age 25 but it widens quickly and steeply during the next five to ten years. Social scientists argue that research proves that much of the widening of the gap is attributable to the wage penalty suffered by married women and by those who have children—what they call the "motherhood penalty."

The "Lifecycle Effect" and the Gender Wage Gap

Many social scientists have documented that the gender wage gap widens with age. Budig, taking a sociological view on the problem, has demonstrated using BLS data that the wage gap in 2012 as measured by median weekly earnings was just 10 percent for those aged 25 to 34 but was more than double that for those aged 35 to 44.

Economists, using different data, have found the same result. Analyzing a combination of quantitative data from the Longitudinal Employer-Household Dynamics (LEHD) database and the 2000 Census long-form survey, a team of economists led by Claudia Goldin, a professor of economics at Harvard University, found that the gender wage gap "widens considerably during the first decade and a half after schooling ends." In conducting their analysis, Goldin's team used statistical methods to rule out the possibility that the gap widens over time due to an increase in discrimination.

They found, conclusively, that the gender wage gap increases with age—especially among the college educated who work in higher-earning jobs than those not requiring a college degree.

In fact, among the college educated, the economists found that 80 percent of the increase in the gap occurs between the ages of 26 and 32. Put differently, the wage gap between college-educated men and women is just 10 percent when they are 25 years old but has widened massively to 55 percent by the time they reach the age of 45. This means that college-educated women lose out on the most earnings, relative to men with the same degrees and qualifications.

Budig argues that the widening of the gender wage gap as people age is due to what sociologists call the "lifecycle effect." Within sociology, "life cycle" is used to refer to the different stages of development that a person moves through during their life, which includes reproduction, and are normatively synced with key social institutions of family and education.

Per Budig, the "lifecycle effect" on the gender wage gap is the effect that certain events and processes that are part of the life cycle have on a person's earnings: namely, marriage and childbirth.

Research Shows that Marriage Hurts the Earnings of Women

Budig and other social scientists see a link between marriage, motherhood and the gender wage gap because there is clear evidence that both life events correspond to a greater gap. Using BLS data for 2012, Budig shows that women who have never been married experience the smallest gender wage gap relative to never-married men—they earn 96 cents to the man's dollar. Married women, on the other hand, earn just 77 cents to the married man's dollar, which represents a gap that is nearly six times greater than that among never-married people.

The effect of marriage on a woman's earnings is made even more clear when looking at the gender wage gap for formerly married men and women. Women in this category earn just 83 percent of what formerly married men earn. So, even when a woman isn't currently married, if she has been, she will see her earnings reduced by 17 percent as compared with men in the same situation.

The same team of economists cited above used the same pairing of LEHD data with long-form Census data to show exactly how marriage impacts the earnings of women in a working paper published by the National Bureau of Economics Research (with Erling Barth, prolific Norwegian economist and a fellow at Harvard Law School, as the first author, and without Claudia Goldin). First, they establish that much of the gender wage gap, or what they call the earnings gap, is created within organizations. Between 25 and 45 years of age, men's earnings within an organization climb more sharply than do those of women. This is true among both the college-educated and non-college educated populations, however, the effect is much more extreme among those with a college degree.

Men with a college degree enjoy vast earnings growth within organizations while women with college degrees enjoy far less.

In fact, their rate of earnings growth is less than that for men without college degrees, and by age 45 is slightly less than that of women without college degrees too. (Keep in mind that we're talking about a rate of earnings growth here, not earnings themselves. College-educated women earn far more than women who do not have college degrees, but the rate at which earnings grow over the course of one's career is about the same for each group, regardless of education.)

Because women earn less than men within organizations, when they change jobs and move to another organization, they do not see the same degree of salary bump—what Barth and his colleagues call an "earnings premium"—when taking the new job. This is especially true for married women and serves to further exacerbate the gender wage gap among this population.

As it turns out, the rate of growth in the earnings premium is about the same for both married and never-married men as well as never-married women through the first five years of a person's career (The rate of growth for never-married women slows after that point.). However, compared to these groups, married women see very little growth in earnings premium over the span of two decades. In fact, it is not until married women are 45 years old that the rate of growth for their earnings premium matches what it was for all others between the ages of 27 and 28. This means that married women have to wait nearly two decades to see the same kind of earnings premium growth that other workers enjoy throughout their working career. Because of this, married women lose out on a significant amount of earnings relative to other workers.

The Motherhood Penalty is the Real Driver of the Gender Wage Gap

While marriage is bad for a woman's earnings, research shows that it is childbirth that really exacerbates the gender wage gap and puts a significant dent in women's lifetime earnings relative to other workers. Married women who are also mothers are hardest hit by the gender wage gap, earning just 76 percent of what married fathers earn, according to Budig. Single mothers earn 86 to the single (custodial) father's dollar; a fact which is in keeping with what Barth and his research team revealed about the negative impact of marriage on a woman's earnings.

In her research, Budig found that women on average suffer a wage penalty of four percent per childbirth during their careers. Budig found this after controlling for the effect on wages of differences in human capital, family structure, and family-friendly job characteristics. Troublingly, Budig also found that low-income women suffer a greater motherhood penalty of six percent per child.

Backing up the sociological findings, Barth and his colleagues, because they were able to match long-form Census data to earnings data, concluded that "most of the loss in earnings growth for married women (relative to married men) occurs concurrently with the arrival of children.”

Yet, while women, especially married and low-income women suffer a "motherhood penalty," most men who become fathers receive a "fatherhood bonus." Budig, with her colleague Melissa Hodges, that men on average receive a six percent pay bump after becoming fathers. (They found this by analyzing data from the 1979-2006 National Longitudinal Survey of Youth.) They also found that, just as the motherhood penalty disproportionately impact low-income women (therefore negatively targeting racial minorities), the fatherhood bonus disproportionately benefits white men—especially those with college degrees.

Not only do these dual phenomena—the motherhood penalty and the fatherhood bonus—maintain and for many, widen the gender wage gap, they also work together to reproduce and worsen already existing structural inequalities that function on the basis of genderrace, and level of education.