Introduction (400 words)
Large-for-gestational-age (LGA) is variously defined as weighing over
4000 grams, 4500 grams, or over the 90th customized
weight for gestational age centile1, 2. It affects
about 10% of all pregnancies.3 Birth of LGA foetuses
has a greater risk of complications including birth trauma, to the
foetus specifically, from shoulder dystocia which can lead to fractures,
brachial plexus injury, perinatal asphyxia, and death, and to the mother
of vaginal tears, haemorrhage, and caesarean section.2A Cochrane review shows that compared with expectant management, early
induction reduces the risk of shoulder dystocia and
fractures.4 A large clinical trial of LGA foetuses
underway in the United Kingdom is also actively exploring whether early
induction of labour starting at 38 weeks will provide perinatal benefits
to the foetus and mother.5
However, there is emerging evidence showing that early-term birth
(37+0-38+6 gestational weeks) may be
associated with reduced cognitive abilities or increased learning
problems in childhood.6-10 Sixteen to 31% of the
population are delivered between 37 to 39 gestational
weeks,11, 12 and a high number of special education
needs (SEN) cases may be attributed to early-term birth. Even small
decreases in cognitive scores can have a marked impact on a child’s
ability to learn and perform academically at school,13and the effects can persist into adulthood,14, 15bringing with them issues of work status and income-earning
capacity.16, 17 The latest UK NHS guidance (2019)
warns of increasing amounts of SEN attributed to early-term
births.18
Considering the adverse effects on cognitive abilities may be confined
to children born with growth restriction, an established risk factor for
cognitive impairment from childhood into adulthood19,
in LGA babies, it is still unclear whether by avoiding one risk (e.g.
shoulder dystocia) we may increase another risk for reduced cognitive or
academic abilities. To date, there are no systematic reviews assessing
the association between LGA babies born at early-term and cognitive or
academic abilities. Existing systematic reviews exploring the effects of
only early-term births on cognitive or academic outcomes do not provide
estimation for each specific week of pregnancy, which is crucial to
induction timing selection.6-10, 20
We aimed to systematically review the available evidence on the
cognitive effects of early-term delivery in LGA babies. However, if we
are unable to find enough existing studies, then instead we will review
the effects of early-term birth and LGA on outcomes independently.