At the outset of the COVID-19 pandemic, the precise extent of the risks in pregnancy was uncertain, which was affecting pregnant individuals’ mental health.^1,2 The lack of clarity arose because, in an early systematic review,³ only 4 studies that involved small numbers compared outcomes between pregnant women with and without COVID-19.^4-7 The question is relevant because of the known deleterious effects of other coronavirus infections in pregnancy (eg, severe acute respiratory syndrome and Middle East respiratory syndrome).⁸ Therefore, the INTERGROWTH-21st Consortium conducted a prospective, longitudinal, observational study (INTERCOVID), involving 43 hospitals in 18 countries, to assess the association between COVID-19 and maternal and neonatal outcomes in pregnant women with COVID-19 diagnosis, compared with concomitantly enrolled pregnant women without COVID-19 diagnosis.

Objective: To establish reference intervals with gestation for the right and left lung areas and lung area to head circumference ratio (LHR).Methods: This was a cross‐sectional study of 650 normal singleton pregnancies at 12–32 weeks of gestation. We measured the left and right lung areas on the cross‐sectional plane of the thorax, used for examination of the four‐chamber view of the heart, by three different techniques: firstly, manual tracing of the limits of the lungs; secondly, multiplication of the longest diameter of the lung by its longest perpendicular diameter; thirdly, multiplication of the anteroposterior diameter of the lung at the mid‐clavicular line by the perpendicular diameter at the midpoint of the anteroposterior diameter.Results: The respective mean left and right lung areas (manual tracing) increased with gestational age, from 36 and 58 mm² at 12 weeks to 220 and 325 mm² at 20 weeks and 594 and 885 mm² at 32 weeks. This 16‐fold increase in lung area was accompanied by a four‐fold increase in head circumference. Consequently, the left and right LHR increased with gestational age. The most reproducible way of measuring the lung area was by manual tracing of the limits of the lungs and the least reproducible was by multiplying the longest diameter of the lungs by their longest perpendicular diameter. Furthermore, the method employing the longest diameter, compared with the tracing method, overestimated both the left and the right lung areas by about 45% and the method employing the anteroposterior diameter overestimated the area of the right lung by about 35%, but not that of the left lung.Conclusions: In the antenatal prediction of pulmonary hypoplasia by the assessment of lung area it is important to take gestational age into account. Dividing the lung area by the head circumference does not correct for the gestation‐related increase in lung area. Reproducible measurement of the lung area is provided by manual tracing of the limits of the lungs, rather than by multiplication of lung diameters. Copyright © 2005 ISUOG. Published by John Wiley & Sons, Ltd.

(Abstracted from JAMA Pediatr 2021;175:817–826) At the beginning of the COVID-19 pandemic, the extent of the risks of a COVID infection during pregnancy were unknown. During the start of the pandemic, there were only a few studies published comparing outcomes between pregnant women with and without COVID-19 infections.