Life-Course Relationship between Socioeconomic Circumstances and Timing of First Birth in a Birth Cohort.

Thea Van Roode,Charlotte Paul,Katrina Sharples,Nigel Dickson,Jacobus P Van Wouwe

doi:10.1371/journal.pone.0170170

Abstract

ObjectivesThis study examines the influence of socioeconomic circumstances in childhood (childhood SES) and adulthood (adult SES) on timing of first birth by age 37.MethodsA longitudinal study of a 1972–1973 New Zealand birth cohort collected information on socioeconomic characteristics from age 3–32 and reproductive histories at 21, 26, 32 and 38; information on first birth was available from 978 of the original 1037. Relative Risks (RR) and 95% Confidence Intervals (CI) were calculated using Poisson regression to examine first live birth prior to age 21, from 21–25, from 26–31, and from 32–37, by socioeconomic characteristics at different ages.ResultsOverall, 68.5% of men had fathered a child and 75.9% of women had given birth, by age 37; with overall differences in parenthood to age 31 for men, and 37 for women evident by childhood SES. While parenthood by age 20 was strongly associated with lower childhood SES for both sexes, first entry into motherhood from 32–37 was more likely with higher adult SES at age 32 (RR = 1.8, 95% CI 1.1–3.0 for medium and RR = 1.9, 95% CI 1.1–3.3 for high compared with low). Education also differientated age at parenthood, with those with higher education more likely to defer fatherhood past age 31, and motherhood past age 25 followed by a period of increased likelihood of motherhood for women with higher levels of education from age 32–37 (RR = 1.4, 95% CI 0.87–2.2 and RR = 1.7, 95% CI 1.1–2.6 for medium and high respectively compared with low).ConclusionsSES varies across the lifecourse, and SES at the time has the strongest association with first births at that time. Low childhood SES drives adolescent parenthood, with resulting cumulative differences in parenthood past age 30. Those with more education and higher adult SES are deferring parenthood but attempt to catch up in the mid to late thirties.

Highlights

Postponement of childbearing is a widespread phenomenon, with many of the more developed countries exhibiting mean ages at birth well exceeding previous generations [1,2,3]
While parenthood by age 20 was strongly associated with lower childhood Socioeconomic Status (SES) for both sexes, first entry into motherhood from 32–37 was more likely with higher adult SES at age 32 (RR = 1.8, 95% Confidence Intervals (CI) 1.1–3.0 for medium and Relative Risks (RR) = 1.9, 95% CI 1.1–3.3 for high compared with low)
Education differientated age at parenthood, with those with higher education more likely to defer fatherhood past age 31, and motherhood past age 25 followed by a period of increased likelihood of motherhood for women with higher levels of education from age 32–37 (RR = 1.4, 95% CI 0.87–2.2 and RR = 1.7, 95% CI 1.1–2.6 for medium and high respectively compared with low)

Summary

Introduction

Postponement of childbearing is a widespread phenomenon, with many of the more developed countries exhibiting mean ages at birth well exceeding previous generations [1,2,3]. Despite this overall shift towards later childbearing, there is still substantial variation in age at first birth within many countries, that may be influenced by socioeconomic circumstances in both childhood and adulthood [3,4]. Causal relationships may be distorted where socioeconomic factors in adulthood are measured at the time of interview, rather than prior to conception, or where data are aggregated at the country level [12,13,14]

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