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The Decline in Fertility: The Role of Marriage and Education

Summary: We relate the decline in the birth rate to two demographic factors closely associated with women’s fertility patterns: marriage and educational attainment. Married women are at least three percentage points more likely to have a child than unmarried women, and simultaneously marriage rates among women 25 to 29 declined 15.9 percent since 2006. Women who complete 4 years of college are less likely to have a child, while completion rates of 4 years of college rose 10 percent for women over the past decade.
Introduction

Over the past decade, fertility declined rapidly in the United States – from a Total Fertility Rate (TFR) of 2.2 births per woman in 2008 to just 1.7 in 2019. Initial reports suggest the effects of the Covid-19 pandemic accelerated this trend. Though some of the pandemic-related fertility decline may be due to families waiting to have children, rather than changing their desired family size.  If this is the case, fertility should rise near the end of the pandemic and in the years directly following the pandemic. This post highlights two demographic trends in women related to the past decade’s decline in fertility: marriage and education.

Marriage and Fertility

Timing of marriage, and particularly whether a woman marries younger or older, has historically been a strong indicator of women’s fertility patterns. Figure 1 depicts age-specific marriage rates among women of childrearing age in 5-year age cohorts from 2006 to 2019, calculated from the American Community Survey (ACS). Over the time period observed, marriage rates among women aged 25-29 dropped 15.9 percentage points.

Figure 1: Age-Specific Marriage Rates Over Time

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Please view online for additonal years.

2019

Figure 2 shows the percentage of women at childrearing age who had a child in the previous year, separately by marital status.1 Over the whole period observed, married women are at least three percentage points more likely to have given birth in the past year than unmarried women. Further, over the past decade unmarried women of childbearing age have grown increasingly unlikely to give birth: the likelihood drops a full percentage point over the time frame observed.

Figure 2: Percentage of women aged 15-49 who had a child last year, by marital status

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Education and Fertility

In women, educational attainment (particularly college attendance), is also closely related to declines in fertility.

Figure 3 displays college education rates among women ages 25 and older. The figure shows a linear rise in completion of four years of college: in 2006, only 30.5 percent of women ages 25 to 49 had completed four years of college, compared to 40.7 percent in 2019.

Figure 3: College Education Rates Among Women Ages 25+

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Figure 4 plots the percentage of women of childrearing age who had a child last year, separately by whether she completed 4 years of college. The birth rates for each of these groups of women declined a full percentage point over the period observed. In 2019, women aged 15-49 with at least four years of college were 0.8 percentage points less likely to have had a child in the past year.

Figure 4: Percentage of women aged 15-49 who had a child last year, by completion of 4 years of college

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Discussion

Examining age-specific fertility rates, marriage rates, and trends in women’s educational attainment, it is clear many women are delaying fertility and ultimately having fewer children. These factors are not isolated, but also interact with one another. A young woman who graduates college is more likely to marry and have children after age 21 and enter the formal labor market. Because she is a worker with a college degree, she likely earns a higher income than women without college degrees meaning her opportunity cost of leaving the labor market to have children will be higher than it otherwise would have been if she earned a lower income. Additionally, if women are concerned that they will progress in their careers at a slower rate if they go on maternity leave, they will also be disincentivized to have children. Further, high childcare costs provide a disincentive for parenthood.

Implications

The decline in birth rates in the US has also been observed in most developed countries around the world.  With the fertility rate being below the 2.1-births-per-woman replacement rate, the resulting population’s age distribution has many policy implications. One concern about declines in fertility is that per capita federal debt will increase for future generations ceteris paribus. For instance, programs like Social Security that are pay-as-you-go systems, will not have enough working age people paying into the program to support the population of retirees without fundamentally changing payroll tax rates or Social Security benefit payouts. Relatedly, there are concerns that a shrinking population would result in a smaller workforce and slower economic growth. Still, others argue that a declining birthrate could have potential positive effects, such as reducing infrastructure costs, and easing ecological burdens and natural resource constraints. One should also keep in mind that increasing immigration could also offset some of the population decline (and effects) that the current trends in the birth rate would cause.



This analysis was conducted by Maddison Erbabian, Austin Herrick, and Victoria Osorio. Prepared for the website by Mariko Paulson.


  1. Marital status is determined by whether the respondent has ever been married, regardless of whether she is married currently.  ↩

  Year	Age Group	Percentage of women who have ever married
  2006	15-19	0.026
  2006	20-24	0.215
  2006	25-29	0.543
  2006	30-34	0.737
  2006	35-39	0.815
  2006	40-44	0.853
  2006	45-49	0.884
  2007	15-19	0.024
  2007	20-24	0.204
  2007	25-29	0.53
  2007	30-34	0.727
  2007	35-39	0.812
  2007	40-44	0.85
  2007	45-49	0.88
  2008	15-19	0.02
  2008	20-24	0.196
  2008	25-29	0.515
  2008	30-34	0.72
  2008	35-39	0.805
  2008	40-44	0.849
  2008	45-49	0.875
  2009	15-19	0.018
  2009	20-24	0.19
  2009	25-29	0.49
  2009	30-34	0.7
  2009	35-39	0.802
  2009	40-44	0.843
  2009	45-49	0.874
  2010	15-19	0.017
  2010	20-24	0.175
  2010	25-29	0.479
  2010	30-34	0.694
  2010	35-39	0.795
  2010	40-44	0.842
  2010	45-49	0.868
  2011	15-19	0.016
  2011	20-24	0.163
  2011	25-29	0.463
  2011	30-34	0.68
  2011	35-39	0.786
  2011	40-44	0.838
  2011	45-49	0.868
  2012	15-19	0.016
  2012	20-24	0.155
  2012	25-29	0.449
  2012	30-34	0.67
  2012	35-39	0.784
  2012	40-44	0.836
  2012	45-49	0.869
  2013	15-19	0.016
  2013	20-24	0.149
  2013	25-29	0.435
  2013	30-34	0.662
  2013	35-39	0.778
  2013	40-44	0.832
  2013	45-49	0.862
  2014	15-19	0.015
  2014	20-24	0.144
  2014	25-29	0.421
  2014	30-34	0.654
  2014	35-39	0.77
  2014	40-44	0.825
  2014	45-49	0.858
  2015	15-19	0.015
  2015	20-24	0.136
  2015	25-29	0.412
  2015	30-34	0.646
  2015	35-39	0.76
  2015	40-44	0.822
  2015	45-49	0.861
  2016	15-19	0.015
  2016	20-24	0.133
  2016	25-29	0.403
  2016	30-34	0.64
  2016	35-39	0.756
  2016	40-44	0.821
  2016	45-49	0.857
  2017	15-19	0.015
  2017	20-24	0.134
  2017	25-29	0.395
  2017	30-34	0.635
  2017	35-39	0.755
  2017	40-44	0.819
  2017	45-49	0.855
  2018	15-19	0.014
  2018	20-24	0.13
  2018	25-29	0.386
  2018	30-34	0.628
  2018	35-39	0.747
  2018	40-44	0.816
  2018	45-49	0.854
  2019	15-19	0.014
  2019	20-24	0.129
  2019	25-29	0.384
  2019	30-34	0.619
  2019	35-39	0.742
  2019	40-44	0.806
  2019	45-49	0.853  
  Year,Percentage of women who completed 4 years of college
  2006,0.305
  2007,0.313
  2008,0.317
  2009,0.326
  2010,0.33
  2011,0.337
  2012,0.346
  2013,0.353
  2014,0.36
  2015,0.37
  2016,0.379
  2017,0.39
  2018,0.399
  2019,0.407  
  Year	EverMarried	Percentage of women who had a child last year
  2006	0	0.040076
  2006	1	0.068384
  2007	0	0.039468
  2007	1	0.069154
  2008	0	0.042001
  2008	1	0.073779
  2009	0	0.041393
  2009	1	0.07264
  2010	0	0.039568
  2010	1	0.069435
  2011	0	0.038092
  2011	1	0.070396
  2012	0	0.03627
  2012	1	0.067904
  2013	0	0.03573
  2013	1	0.069148
  2014	0	0.03522
  2014	1	0.069907
  2015	0	0.034373
  2015	1	0.069827
  2016	0	0.033926
  2016	1	0.072189
  2017	0	0.0325
  2017	1	0.073227
  2018	0	0.031425
  2018	1	0.073254
  2019	0	0.029348
  2019	1	0.072421
  year	College	Percentage of women who had a child last year
  2006	0	0.054652
  2006	1	0.063453
  2007	0	0.054974
  2007	1	0.06219
  2008	0	0.058302
  2008	1	0.06596
  2009	0	0.057145
  2009	1	0.064293
  2010	0	0.05468
  2010	1	0.060216
  2011	0	0.053366
  2011	1	0.062165
  2012	0	0.051356
  2012	1	0.058565
  2013	0	0.051304
  2013	1	0.059156
  2014	0	0.051021
  2014	1	0.059412
  2015	0	0.050483
  2015	1	0.058332
  2016	0	0.050901
  2016	1	0.060032
  2017	0	0.050681
  2017	1	0.059567
  2018	0	0.049985
  2018	1	0.058722
  2019	0	0.048533
  2019	1	0.056674