Introduction
Placental abruption is a significant obstetric complication that affects
both maternal and neonate mortality and morbidity. It is defined as the
premature partial or total separation of a normally implanted
placenta.1 Maternal consequences include excessive
blood loss and disseminated intravascular coagulation (DIC), which
sometimes needs blood transfusion and can lead to hypovolemic shock,
multiorgan failure, peripartum hysterectomy, and rarely,
death.2,3 Neonatal consequences include preterm birth
and related hypoxia or an asphyxia condition.1,4 Fetal
asphyxia combined with prematurity can be associated with short-term
sequelae such as neonatal encephalopathy/hypoxic-ischemic encephalopathy
and long-term sequelae such as cerebral palsy, lung diseases, and
epilepsy.1,5
The prevalence of placental abruption varies across regions.
In some countries, the prevalence
of placental abruption is increasing, possibly due to changes in the
risk factors,2 including increasing maternal age, body
mass index, and increasing use of assisted reproductive technology (ART)
since the past decade. Maternal age is one of the key risk factors for
placental abruption. In 1993, a prospective cohort study comprising
30,681 participants with singleton pregnancies reported that the risk of
placental abruption increased in a year (odds Ratio [OR] 1.03, 95%
confidential interval [CI] 1.00–1.06, p = 0.04).6The statistic reports suggest that the mean maternal age is increasing
in Japan.7Although a recent Japanese birth
cohort study reported that increasing maternal age is a risk factor for
preterm delivery and fetal growth restriction,8teenage maternal age is also a risk factor for severe maternal obstetric
complications such as hypertensive disorders of pregnancy (HDP) and
placental abruption.9 Owing to the changes in social
background during the last decade, up-to-date evidence for the effect of
maternal age on placental abruption is required.
Several studies have focused on
the advanced maternal age as a risk factor for placental abruption.
However, a few prospective studies have comprehensively assessed both
teenage and advanced maternal age as risk factors for placental
abruption, while accounting for several confounding factors using a
large number of participants. Therefore, the present study, including
the participants from the largest prospective birth cohort study in the
Japanese population conducted between 2011 and 2014, examined the effect
of maternal age on placental abruption.