Defined as women’s health during pregnancy, perinatal health is an important aspect of public health. However, the effects of the COVID-19 pandemic on healthy pregnant women without COVID-19 infection remain unknown. Pregnant women are regarded as a “vulnerable population” because they are more sensitive to environmental factors, including stress, than the general population. However, women may become decreasingly sensitive to the effects of stress as pregnancy advances (19).
The focus of study is only on uncomplicated singleton pregnancies among women not infected by COVID-19. Our results show that the survey results indicate that there were no differences in the basic characteristics of the two groups, suggesting no significant differences in baseline measurements of health. The total number of white blood cells, ALT, and AST are sensitive biochemical indicators, and the concentrations of these indicators slightly increased but varied within the normal range under stressful conditions (Table 2). Although the proportion of neutrophils and lymphocytes in the observed group was lower than that in the control group, we speculate that this difference did not result in adverse outcomes of pregnant women given that the amounts of ALT and AST were within the normal range of deviation, and there was no difference in the number of white blood cells. The haemoglobin level in pregnant women in the observed group was higher than that in the control group, which may be a beneficial result of nutrition intake (20).
Labour and delivery are affected by many factors, such as maternal history, environmental and behavioural factors, as well as socio-demographic factors (i.e., race, age, and marital status) (21, 22). Accumulating evidence suggests that extrinsic stress is closely associated with terrible birth outcomes (23), broadening the concept of social determinants of a healthy birth. Previous studies have shown that there are controversial conclusions for determining the key factors to maintain healthy birth in response to natural disasters (24) (25) (26) (27). In agreement with the effect of the Gulf of Mexico oil spill on adverse maternal outcomes (27), this survey found that pregnancy complications, including preeclampsia, gestational hypertension, premature rupture of membranes, and preterm delivery, did not significantly increase during the COVID-19 outbreak compared to the control period (Table 3). Interestingly, we observed several health indicators in pregnant women in the research group, such as slightly longer pregnancy, increased rate of spontaneous vaginal delivery, and reduction of PPH and postnatal psychological morbidity (Table 4). There are several possible explanations for this finding. i) People stayed at home in order to minimise the spread of COVID-19. In particular, pregnant women may be particularly sensitive to self-preservation, and they unconsciously reduced the frequency of ongoing prenatal care (FPC) and prolonged the intervals for prenatal visits to minimise infection risk. Consequently, among symptomatic pregnant women, gestational age was often prolonged because women were not admitted to the hospital timely in a timely fashion. Furthermore, the higher rate of vaginal births may have been due to the reduction of preventive, diagnostic and therapeutic medical interventions. ii) The substantial decrease in the number of people going out was accompanied by blood product shortages, leading obstetricians to become more active participants in the prevention and treatment of PPH. Both the reduction in women who received midwifery care and the increase in the number of spontaneous vaginal deliveries resulted in the reduction of PPH. Although the survey results showed that occurrences of perineal laceration increased in the research group compared with the data in the same period in 2019, we did not find that it affected the average amount of PPH, which suggests that this may have been due to superficial lacerations, less bleeding, and suture and effective haemostasis.
Our study showed that the rate of neonatal infections was reduced, which seems to be associated with the health actions of pregnant women during delivery. Although the survey showed a decrease in the proportion of patent foramen ovale, we did not consider this to be an abnormal indicator, since it is a common phenomenon even in healthy newborns, most of which close spontaneously 7 days postpartum or even after giving birth (28, 29). Therefore, we could not classify the observation in newborns as congenital heart disease.
Our study showed an increase in the prevalence of 25-hydroxyvitamin D deficiency and zinc deficiency, important elements of foetal growth and development, in newborns in the research group. As an important nutrient in bone health, vitamin D inadequacy may increase the risk of fractures, rickets, osteomalacia, and osteoporosis. Because humans generate vitamin D with the help of sunlight (30), seasonal changes in addition to the use of dietary supplements can also influence the intake of vitamin D (31–33). The growth and development of the foetus in the uterus are completely dependent on the mother; thus, the storage of vitamin D during pregnancy plays an important role in foetal growth (34). It has been shown that vitamin D deficiency in pregnant women occurs more frequently in winter than in summer (35). Hence, we speculate that the home quarantine measures during the COVID-19 pandemic reduced the sunlight exposure of pregnant women, causing maternal vitamin D deficiency and eventually increasing the prevalence of 25-hydroxyvitamin D deficiency in the newborns.
Since these trace elements in newborn babies mainly come from the mother, low serum zinc levels during pregnancy can easily lead to zinc deficiency in infants. Regarding the increased prevalence of newborns’ zinc deficiency in the research group, it is speculated that changes in pregnant women’s dietary structure during the COVID-19 epidemic would interfere with the mean intakes of mineral and trace elements from food. However, this retrospective study provides very limited support for this theory because it failed to monitor the levels of trace elements and vitamins in pregnant women in the research and control groups. For that reason, more rigorous studies are certainly required to reveal the underlying mechanisms involved in neonatal vitamin D and zinc deficiency.
To further verify the impact of the COVID-19 epidemic on maternal and newborn outcomes, we compared one more set of data of pregnant women and newborns as another control group, which was taken from the period (i.e., from 1 January 2020 to 23 January 2020) prior to outbreak of COVID-19 (Table S1-S6). There was no difference in the health indicators of pregnant women between the research and control groups. Compared to this control group, both the haemoglobin levels in pregnant women and PPH in the research group were comparatively improved. It is worth noting that the incidences of both neonatal zinc and 25 hydroxyvitamin D deficiencies in the research group were higher than in this control group, while the incidence of patent foramen ovale in the research group was lower. However, inconsistent with the previous comparison, we observed a lower incidence of preeclampsia and upper respiratory tract infections, premature delivery, low birth weight, patent ductus arteriosus, and hyperbilirubinaemia and hypoproteinaemia. The comparison of the two groups further confirmed that there were no adverse outcomes of pregnant women or newborns during the COVID-19 epidemic; the outcome of newborns during COVID-19 seemed to be better than those in the absence of COVID-19. In contrast, the outcomes seemed better from the view of the newborn during COVID-19 compared the data prior to the pandemic.
In conclusion, this study revealed that the quarantine measures during the COVID-19 epidemic did not substantially negatively affect maternal or neonate outcomes, which may have been associated with the previous SARS epidemic in Guangzhou. Moreover,improvements in the quality of rest at home as a result of quarantine measures during the COVID-19 epidemic might have yielded more benefits to maternal and infant outcomes. Nevertheless, the vitamin D and zinc deficiencies identified in newborn during the COVID-19 epidemic should draw attention.