Variables
Outcome Variables:
Neonatal birth weight (BW), head circumference (HC) and length (Lt) were
the main outcome variables. Gestational age at delivery and the need for
admission to the special care baby unit were also recorded.
Demographics and pregnancy variables:
In order to describe the study population, we focused on psychosocial
and demographic factors impacting birth weight: maternal age, infant
gender, ethnic origin, maternal height, maternal weight before
pregnancy, maternal weight gain during pregnancy, parity,
pregnancy-induced hypertensive disorder, gestational diabetes, preterm
birth <37 weeks of gestation, smoking status and high-risk
pregnancy.
Gestational age and trimester based on gestational age at the beginning
of the COVID-19 lockdown in Spain (14 March 2020) were calculated for
each participant so as to identify the time when anxiety symptoms due to
the COVID-19 lockdown may have appeared.
Maternal body mass index (BMI) at the beginning of the pregnancy was
calculated based on weight before pregnancy (kg)/height
(m2).
The local protocol of the antenatal clinic was used to identify
participants with high-risk pregnancies.
Psychosocial questionnaires:
During visits to the antenatal clinic, several questionnaires were
prospectively administered to detect anxiety and depression symptoms, as
well as the absence of social support.
The EPDS is a 10-item self-reported scale designed to specifically
detect postpartum depression. Each item is rated on a 4-point scale
ranging from 0 to 3, with higher scores indicating a greater severity of
the depression. The Spanish validation of the EPDS gave an optimal
cut-off value of 10/11 for combined major and minor depression,
sensitivity was 79%, and specificity was 95.5%, with a positive
predictive value of 63.2% and a negative predictive value of 97.7%. In
addition, a cut-off value of 13 has a sensitivity of 62%, and a
specificity of 98.1%, with a positive predictive value of 76.5% and a
negative predictive value of 96.4%. The gold standard for the diagnosis
of postpartum depression is an assessment during a clinical interview
with a mental health professional.
The STAI is a 40-item self-reported scale designed to detect state
anxiety (STAIs) and trait anxiety (STAIt). The STAI is the most used
rating scale for measuring anxiety symptoms. Its validity and
reliability have been carefully evaluated. Each item is rated on a
4-point scale ranging from 0 to 3, with higher scores indicating a
greater severity of the anxiety. For comparison to international
studies, the 0-3 range in the 4-point scale has been changed to 1-4, as
in those studies. The STAI scale has also been validated to use it in
pregnant women. Range of scores for each subtest is 20–80, with higher
scores indicating a greater severity of the anxiety. A cut-off value of
39–40 has been suggested as a value able to detect clinically
significant symptoms of anxiety scale.
Finally, the Medical Outcomes Study Social Support Survey (MOS-SSS) is a
20-item self-reported questionnaire developed by the Rand and Medical
Outcomes Study teams to measure the level of social support. This scale
measures positive social interactions, as well as tangible, affectionate
and emotional/informational support. The MOS-SSS has shown good
reliability and validity. The Spanish version of the MOS-SSS has also
been validated, showing satisfactory psychometric properties.