INTRODUCTION
Fetal growth restriction is a common pregnancy complication, and is
considered a leading cause of stillbirth, neonatal mortality, and short-
and long-term neonatal morbidity. Low birth weight, typically defined as
a birth weight below the 10th percentile for
gestational age, affects around 10% of births in Spain and up to
26-28% of births in underdeveloped regions of Africa and Asia.
Low birth weight is associated with increased morbidity in infants,
children, and adults. Some morbidities associated with fetal growth
restriction are increased risk of preterm birth, delayed child
development, poor speech, and adolescence mental health disorders.
There are several maternal risk factors for low birth weight, such as
advanced maternal age, ethnic origin, consanguinity, low body mass
index, nulliparity, use of recreational drugs, alcohol, assisted
reproductive techniques, congenital infections, and chronic medical
disorders, such as chronic hypertension or diabetes mellitus. Another
factor associated with low birth weight is maternal anxiety during
pregnancy.
Anxiety is an emotion characterized by apprehension and somatic symptoms
of tension in which an individual anticipates impending danger,
catastrophe, or misfortune. The prevalence of anxiety disorder in the
general population is 13.6%, but increases to 15.2% during pregnancy.
Researchers discriminate between state anxiety and trait anxiety. While
state anxiety refers to a transient reaction to a stressful situation,
trait anxiety is defined as a more persistent personality trait.
Comparatively, less research has been conducted on the role of
personality predisposition to anxiety.
There is conflicting data regarding the effect of maternal psychological
distress on fetal growth. The fetoplacental-maternal unit may regulate
fetal growth according to the type of psychological distress following a
stressful event and even increase fetal growth in response to maternal
stress in major areas of life. In addition, the effect of anxiety timing
on birth weight is not well understood, and data shows opposing
outcomes.
Briefly, while it is clear that anxiety during pregnancy is associated
with a lower birth weight, it is not clear whether there are any
differences on the effects of anxiety based on whether it is trait or
state anxiety, or whether the impact of anxiety is different depending
on the gestational age at which anxiety symptoms arise.
Therefore, the aim of this study was to study the effects of maternal
anxiety on fetal growth. Secondary objectives were to investigate the
effect of anxiety timing and the potentially different effects of trait
anxiety and state anxiety on fetal growth.