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.