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.