Maternal age as a predictive factor of pre-term birth. An epidemiological study from 1999 to 2008 in Greece

Abstract

The aim of the study was to estimate the risk of pre-term birth in women giving birth in Greece in different age groups. Data about women giving birth in Greece were retrieved from the Hellenic Vital Statistics covering the years from 1999 to 2008. Relative risk using χ(2) contingency tables was estimated among maternal age groups formed. These groups included mothers < 15 years of age, 15-19, 20-34 (used as a control group) and women > 34 (35-39, 40-44, 45-49 and ≥ 50) years of age. Relative risk of each age group was compared with mothers 20-34 years of age. A total of 1,069,413 valid births were included in the study and 72,156 of them were pre-term (6.75% of total count). Results exhibit a 'U'-shaped distribution of risk. Higher risk of pre-term birth is noted in the groups of < 15 years (Pearson χ(2) = 14.964, p < 0.001, risk = 1.569, CI = 1.249-1.970) and above 34 years of age (Pearson χ(2) = 2991.26, p < 0.001, risk = 1.572, CI = 1.546-1.597). For older women, a steep rise in the relative risk for pre-term birth was noted beyond the 40-44 years of age group. Finally, of interest is the fact that 'late' pre-terms (34-36 gestational weeks) account for most of the pre-term birth in mothers beyond 34 years of age.

Perinatal outcomes, maternal age, parity and fetal sex – searching for the “optimal” maternal age

“…The preterm delivery was 2 times more common in multiparous women who gave birth to a boy and the likelihood of preterm birth decreased in multiparous women who gave birth to a girl in comparison to the control group (age 20-39). These findings are largely consistent with those of other relevant studies showing that women of advanced maternal age are at greater risk for having preterm birth [10,27]. A higher incidence of preterm birth has been observed among mothers of male newborns compared with mothers of females [17], however, no work has documented the combination of dependence between sex, parity, and age.…”

“…female newborns. The 174 age limits for the comparison of risks of adverse delivery outcomes were determined based on 175 the results of previous studies focused on the study of similar variables [7,11,27,28]. The 176 odds of preterm delivery, low birth weight, macrosomia > 4,500g and caesarean delivery were 177 statistically compared in selected age groups for primiparous resp.…”

Risk Assessment of Adverse Birth Outcomes in Relation to Maternal Age

“…In addition, the birth weight and gestational age are important indicators of neonatal morbidity and mortality. An increasing number of publications have shown that pregnancies by teenagers and women of advance maternal age, defined as ≥35 years of age, are at greater risk for stillbirth, preterm birth, and low birth weight [1] – [22] . Researchers analyzed the relationship between maternal age and adverse birth outcomes by adjusting for maternal socio-economic status (such as prenatal care, marital status, residence, educational level, tobacco and alcohol consumption, and ethnicity) [1] , [6] – [11] , obstetric conditions (such as multiple pregnancy, parity, delivery mode, and pregnancy-related complications) and neonatal outcomes (such as stillbirth, gender, Apgar score, birth weight, and gestational age) [1] , [2] , [4] , [6] – [16] .…”

Preterm birth trends in Greece, 1980–2008: a rising concern

“…The prevalent maternal age group during 1980 was 20-24 years of age, whereas early in the new century the prevalent age group was 30-34 years (25). We have demonstrated elsewhere that women over 34 years in Greece have an increased risk of preterm birth compared with women 20-24 years of age (29). Given that by the year 2008 mothers over 34 years accounted for 20.9% of mothers giving birth, compared with 6.9% during the year 1980, we can reasonably conclude that this trend partially explains the rise in the number of preterm births in the country.…”