COVID-19 pandemic and population-level pregnancy and neonatal outcomes in general population: A living systematic review and meta-analysis (Update#2: November 20, 2021)

Social distancing and extremely preterm births in the initial COVID-19 pandemic period

HYPOTHESIS

Increased social distancing was associated with a lower incidence of extremely preterm live births (EPLB) during the initial COVID-19 pandemic period.

STUDY DESIGN

Prospective study at the NICHD Neonatal Research Network sites comparing EPLB (220/7-286/7 weeks) and extremely preterm intrapartum stillbirths (EPIS) rates during the pandemic period (March-July, weeks 9-30 of 2020) with the reference period (same weeks in 2018 and 2019), correlating with state-specific social distancing index (SDI).

RESULTS

EPLB and EPIS percentages did not significantly decrease (1.58-1.45%, p = 0.07, and 0.08-0.06%, p = 0.14, respectively). SDI was not significantly correlated with percent change of EPLB (CC = 0.29, 95% CI = -0.12, 0.71) or EPIS (CC = -0.23, 95% CI = -0.65, 0.18). Percent change in mean gestational age was positively correlated with SDI (CC = 0.49, 95% CI = 0.07, 0.91).

CONCLUSIONS

Increased social distancing was not associated with change in incidence of EPLB but was associated with a higher gestational age of extremely preterm births.

CLINICALTRIALS

GOV ID

Generic Database: NCT00063063.

Association between maternal and perinatal outcomes and histological changes in the placenta of patients with Covid-19: A cohort study

Although studies evaluated placental involvement in Covid-19 patients, few have assessed its association with clinical repercussions. The study aimed to determine the association between the clinical status and maternal and perinatal outcomes of patients with Covid-19 at delivery and changes in placental histology. It is so far the largest cohort evaluating placentas of patients infected by the SARS-CoV-2. A secondary analysis was conducted of a database from which a cohort of 226 patients, who tested real-time polymerase chain reaction-positive for Covid-19 at delivery and whose placentas were collected and submitted to pathology, was selected for inclusion. One or more types of histological changes were detected in 44.7% of the 226 placentas evaluated. The most common abnormalities were maternal vascular malperfusion (38%), evidence of inflammation/infection (9.3%), fetal vascular malperfusion (0.8%), fibrinoid changes and intervillous thrombi (0.4%). Oxygen use (P = .01) and need for admission to an intensive care unit (ICU) (P = .04) were less common in patients with placental findings, and hospital stay was shorter in these patients (P = .04). There were more fetal deaths among patients with evidence of inflammation/infection (P = .02). Fetal death, albeit uncommon, is associated with findings of inflammation/infection. Oxygen use and need for admission to an ICU were less common among patients with placental findings, probably due to the pregnancy being interrupted early. None of the other findings was associated with maternal clinical status or with adverse perinatal outcome.

SARS-CoV-2 infection by trimester of pregnancy and adverse perinatal outcomes: a Mexican retrospective cohort study

OBJECTIVE

Conflicting evidence for the association between COVID-19 and adverse perinatal outcomes exists. This study examined the associations between maternal COVID-19 during pregnancy and adverse perinatal outcomes including preterm birth (PTB), low birth weight (LBW), small-for-gestational age (SGA), large-for-gestational age (LGA) and fetal death; as well as whether the associations differ by trimester of infection.

DESIGN AND SETTING

The study used a retrospective Mexican birth cohort from the Instituto Mexicano del Seguro Social (IMSS), Mexico, between January 2020 and November 2021.

PARTICIPANTS

We used the social security administrative dataset from IMSS that had COVID-19 information and linked it with the IMSS routine hospitalisation dataset, to identify deliveries in the study period with a test for SARS-CoV-2 during pregnancy.

OUTCOME MEASURES

PTB, LBW, SGA, LGA and fetal death. We used targeted maximum likelihood estimators, to quantify associations (risk ratio, RR) and CIs. We fit models for the overall COVID-19 sample, and separately for those with mild or severe disease, and by trimester of infection. Additionally, we investigated potential bias induced by missing non-tested pregnancies.

RESULTS

The overall sample comprised 17 340 singleton pregnancies, of which 30% tested positive. We found that those with mild COVID-19 had an RR of 0.89 (95% CI 0.80 to 0.99) for PTB and those with severe COVID-19 had an RR of 1.53 (95% CI 1.07 to 2.19) for LGA. COVID-19 in the first trimester was associated with fetal death, RR=2.36 (95% CI 1.04, 5.36). Results also demonstrate that missing non-tested pregnancies might induce bias in the associations.

CONCLUSIONS

In the overall sample, there was no evidence of an association between COVID-19 and adverse perinatal outcomes. However, the findings suggest that severe COVID-19 may increase the risk of some perinatal outcomes, with the first trimester potentially being a high-risk period.

Evaluation of pregnancy outcomes in mothers with COVID-19 infection: a systematic review and meta-analysis

Pregnant women are one of the endangered groups who need special attention in the COVID-19 epidemic. We conducted a systematic review and summarised the studies that reported adverse pregnancy outcomes in pregnant women with COVID-19 infection. A literature search was performed in PubMed and Scopus up to 1 September 2022, for retrieving original articles published in the English language assessing the association between COVID-19 infection and adverse pregnancy outcomes. Finally, in this review study, of 1790 articles obtained in the initial search, 141 eligible studies including 1,843,278 pregnant women were reviewed. We also performed a meta-analysis of a total of 74 cohort and case-control studies. In this meta-analysis, both fixed and random effect models were used. Publication bias was also assessed by Egger's test and the trim and fill method was conducted in case of a significant result, to adjust the bias. The result of the meta-analysis showed that the pooled prevalence of preterm delivery, maternal mortality, NICU admission and neonatal death in the group with COVID-19 infection was significantly more than those without COVID-19 infection (p<.01). A meta-regression was conducted using the income level of countries. COVID-19 infection during pregnancy may cause adverse pregnancy outcomes including of preterm delivery, maternal mortality, NICU admission and neonatal death. Pregnancy loss and SARS-CoV2 positive neonates in Lower middle income are higher than in High income. Vertical transmission from mother to foetus may occur, but its immediate and long-term effects on the newborn are unclear.

The COVID-19 pandemic affects pregnancy complications and delivery outcomes in Japan: a large-scale nationwide population-based longitudinal study

The impact of the coronavirus disease 2019 (COVID-19) pandemic on pregnancy outcomes in Japan at the national level is unclear. This study aimed to assess the impact of the pandemic on pregnancy complications and delivery outcomes in Japan using nationwide population-based longitudinal data. Secondary data from the Japan Society of Obstetrics and Gynecology from 2016 to 2020 were analyzed. Obstetric information, pregnancy complications, and delivery information of pregnant women over 22 weeks of gestation were compared before and during the pandemic. The trends of hypertensive disorder of pregnancy, fetal growth restriction, and APGAR < 7 increased, whereas those of preterm birth and low birth weight decreased during the COVID-19 pandemic. Pregnancy complications and delivery outcomes have worsened during the COVID-19 pandemic in Japan. Social changes caused by unprecedented situations may have massively influenced pregnancy in several ways. Our findings suggest that even in mild lockdowns like those in Japan, the introduction of social fear during the pandemic might negatively impact pregnancy outcomes.

Infant death prediction using machine learning: A population-based retrospective study

BACKGROUND

Despite declines in infant death rates in recent decades in the United States, the national goal of reducing infant death has not been reached. This study aims to predict infant death using machine-learning approaches.

METHODS

A population-based retrospective study of live births in the United States between 2016 and 2021 was conducted. Thirty-three factors related to birth facility, prenatal care and pregnancy history, labor and delivery, and newborn characteristics were used to predict infant death.

RESULTS

XGBoost demonstrated superior performance compared to the other four compared machine learning models. The original imbalanced dataset yielded better results than the balanced datasets created through oversampling procedures. The cross-validation of the XGBoost-based model consistently achieved high performance during both the pre-pandemic (2016-2019) and pandemic (2020-2021) periods. Specifically, the XGBoost-based model performed exceptionally well in predicting neonatal death (AUC: 0.98). The key predictors of infant death were identified as gestational age, birth weight, 5-min APGAR score, and prenatal visits. A simplified model based on these four predictors resulted in slightly inferior yet comparable performance to the all-predictor model (AUC: 0.91 vs. 0.93). Furthermore, the four-factor risk classification system effectively identified infant deaths in 2020 and 2021 for high-risk (88.7%-89.0%), medium-risk (4.6%-5.4%), and low-risk groups (0.1), outperforming the risk screening tool based on accumulated risk factors.

CONCLUSIONS

XGBoost-based models excel in predicting infant death, providing valuable prognostic information for perinatal care education and counselling. The simplified four-predictor classification system could serve as a practical alternative for infant death risk prediction.

The impact of prenatal maternal mental health during the COVID-19 pandemic on birth outcomes: two nested case-control studies within the CONCEPTION cohort

OBJECTIVE

Assess the association between prenatal mental health during the COVID-19 pandemic and preterm birth (PTB; delivery < 37 weeks gestation) and low birth weight (LBW; < 2500 g).

METHODS

Pregnant individuals, > 18 years, were recruited in Canada and provided data through a web-based questionnaire. We analyzed data on persons recruited between 06/2020 and 08/2021 who completed questionnaires while pregnant and 2 months post-partum. Data on maternal sociodemographics, comorbidities, medication use, mental health (Edinburgh Postnatal Depression Scale, General Anxiety Disorder-7, stress), pandemic hardship (CONCEPTION-Assessment of Stress from COVID-19), and on gestational age at delivery and birth weight were self-reported. Crude and adjusted odds ratios (aOR) with 95% confidence interval (95%CI) were calculated to quantify the association between PTB/LBW and maternal mental health.

RESULTS

A total of 1265 and 1233 participants were included in the analyses of PTB and LBW, respectively. No associations were observed between PTB and prenatal mental health (depression [aOR 1.01, 95%CI 0.91-1.11], anxiety [aOR 1.04, 95%CI 0.93-1.17], stress [aOR 0.88, 95%CI 0.71-1.10], or hardship [aOR 1.00, 95%CI 0.96-1.04]) after adjusting for potential confounders. The risk of PTB was increased with non-white ethnicity/race (aOR 3.85, 95%CI 1.35-11.00), consistent with the literature. Similar findings were observed for LBW (depression [aOR 1.03, 95%CI 0.96-1.13], anxiety [aOR 1.05, 95%CI 0.95-1.17], COVID stress [aOR 0.92, 95%CI 0.77-1.09], or overall hardship [aOR 0.97, 95%CI 0.94-1.01]).

CONCLUSION

No association was found between prenatal mental health nor hardship during the COVID-19 pandemic and the risk of PTB or LBW. However, it is imperative to continue the follow-up of mothers and their offspring to detect long-term health problems early.

Preterm births prevalence during the COVID-19 pandemic in Brazil: results from the national database

The SARS-CoV-2 (COVID-19) pandemic impacted the health systems between and within countries, and in the course of the pandemic sexual and reproductive health services were the most disrupted. Findings from high-income settings have reported significant changes in preterm birth prevalence during the pandemic period. To understand the possible effects of the COVID-19 pandemic on preterm birth numbers at the Brazilian national level. We compare the number of preterm deliveries during the COVID-19 pandemic period (2020 and 2021) with previous years. We conducted a population-based cross-sectional study taking the period from January 2017 to December 2021 to account. We use individual-level live births data from the Brazilian Live Birth Information System (SINASC), and we estimate the odds ratio (OR) of preterm deliveries using propensity score weighting analysis in Brazil and its regions. During the study period (from 2017 to 2021), about 2.7 million live births were recorded per year, and the missing value for gestational age at delivery was less than 1.5%. The preterm birth prevalence slightly increased during the COVID-19 pandemic compared to the pre-pandemic period (11.32% in 2021 vs 11.09% in 2019, p-value < 0.0001). After adjusting for sociodemographic variables, the OR of preterm births in Brazil has significantly increased, 4% in 2020 (OR: 1.04 [1.03-1.05] 95% CI, p-value < 0.001), and 2% in 2021(OR: 1.02 [1.01-1.03] 95% CI, p-value < 0.001), compared to 2019. At the regional level, the preterm birth pattern in the South, Southeast and Northeast regions show a similar pattern. The highest odds ratio was observed in the South region (2020 vs 2019, OR: 1.07 [1.05-1.10] 95% CI; 2021 vs 2019, OR: 1.03 [1.01-1.06] 95% CI). However, we also observed a significant reduction in the ORs of preterm births in the northern region during the COVID-19 pandemic (2020 vs 2019, OR: 0.96 [0.94-0.98] 95% CI) and (2021 vs 2019, OR: 0.97 [0.95-0.99] 95% CI). Our analysis shows that the pandemic has increased regional variation in the number of preterm births in Brazil in 2020 and 2021 compared to the pre-pandemic years.

Prenatal maternal stress during the COVID-19 pandemic and birth outcomes: Is the newborn spared?

The COVID-19 pandemic has generated numerous stressors among the general population, but more specifically in pregnant women because of disruptions in prenatal care and delivery conditions. Studies suggest that prenatal maternal stress increased during the pandemic (Berthelot et al., 2020; Perzow et al., 2021; Tomfohr-Madsen et al., 2021). Considering what is known about the fetal programming potential of prenatal maternal stress, several researchers, early in the pandemic, raised concerns over the significant negative consequences that the pandemic context could have on birth outcomes. Studies comparing birth outcomes during versus before the pandemic suggest a marginal increase in birthweight and a significant decrease in preterm birth (Yang et al., 2022), but individual variations in prenatal maternal stress during the pandemic have received less attention. The objective of the present study is to examine the association between prenatal maternal stress during the COVID-19 pandemic and birth outcomes. During pregnancy, 195 expecting mothers reported on their general and pandemic-related stress. When their child was 6 months old, mothers completed a questionnaire collecting information on birth outcomes (gestational age, birthweight, head circumference and Apgar scores). Hierarchical linear regressions show that none of the maternal prenatal stress variables significantly predicted variations in birth outcomes. Potential pandemic-related protective factors (e.g., changes in life and hygiene habits, rest imposed by lockdowns) and the need to offer support to pregnant women are discussed.

An evaluation of the association between lockdown during the SARS-CoV-2 pandemic and prematurity at the Nice University Hospital

Aim

To study the association between lockdown in France due to the SARS-CoV-2 pandemic and premature births at the Nice University Hospital.

Methods

Data concerning neonates born at the level III maternity of the Nice University Hospital and immediately hospitalised in the neonatal reanimation unit or the neonatology department of the hospital with their mothers between the 1st of January 2017 and the 31st of December 2020, included.

Results

We did not find a significant decrease in the global number of premature births <37 weeks of gestation, in low weight at birth or a significant increase in stillbirths during lockdown compared to a period with no lockdown. The profiles of the mothers and their newborns were compared when birth occurred during lockdown vs. no lockdown.

Conclusion

We did not find any evidence of an association between lockdown and prematurity at the Nice University Hospital. This result is in agreement with meta-analyses published in the medical literature. The possible decrease in factors of risk of prematurity during lockdown is controversial.

Small babies, big risks: global estimates of prevalence and mortality for vulnerable newborns to accelerate change and improve counting

Small newborns are vulnerable to mortality and lifelong loss of human capital. Measures of vulnerability previously focused on liveborn low-birthweight (LBW) babies, yet LBW reduction targets are off-track. There are two pathways to LBW, preterm birth and fetal growth restriction (FGR), with the FGR pathway resulting in the baby being small for gestational age (SGA). Data on LBW babies are available from 158 (81%) of 194 WHO member states and the occupied Palestinian territory, including east Jerusalem, with 113 (58%) having national administrative data, whereas data on preterm births are available from 103 (53%) of 195 countries and areas, with only 64 (33%) providing national administrative data. National administrative data on SGA are available for only eight countries. Global estimates for 2020 suggest 13·4 million livebirths were preterm, with rates over the past decade remaining static, and 23·4 million were SGA. In this Series paper, we estimated prevalence in 2020 for three mutually exclusive types of small vulnerable newborns (SVNs; preterm non-SGA, term SGA, and preterm SGA) using individual-level data (2010-20) from 23 national datasets (∼110 million livebirths) and 31 studies in 18 countries (∼0·4 million livebirths). We found 11·9 million (50% credible interval [Crl] 9·1-12·2 million; 8·8%, 50% Crl 6·8-9·0%) of global livebirths were preterm non-SGA, 21·9 million (50% Crl 20·1-25·5 million; 16·3%, 14·9-18·9%) were term SGA, and 1·5 million (50% Crl 1·2-4·2 million; 1·1%, 50% Crl 0·9-3·1%) were preterm SGA. Over half (55·3%) of the 2·4 million neonatal deaths worldwide in 2020 were attributed to one of the SVN types, of which 73·4% were preterm and the remainder were term SGA. Analyses from 12 of the 23 countries with national data (0·6 million stillbirths at ≥22 weeks gestation) showed around 74% of stillbirths were preterm, including 16·0% preterm SGA and approximately one-fifth of term stillbirths were SGA. There are an estimated 1·9 million stillbirths per year associated with similar vulnerability pathways; hence integrating stillbirths to burden assessments and relevant indicators is crucial. Data can be improved by counting, weighing, and assessing the gestational age of every newborn, whether liveborn or stillborn, and classifying small newborns by the three vulnerability types. The use of these more specific types could accelerate prevention and help target care for the most vulnerable babies.

Effect of COVID-19 on Pregnancy and Neonate's Vital Parameters: A Systematic Review

Background

COVID-19 is a new pandemic, which was declared by the World Health Organization in 2019 as a threat to public health. According to numerous reports, it can have negative consequences for pregnant women, labour, and neonates born to infected mothers. The aim of this paper was to gather the evidence and to present a summary of the results of studies concerning COVID-19 in pregnant women and their neonates.

Methods

Articles from prestigious journals covering the period from 2020 to February 2023, relevant review papers, and original research articles from PubMed were analysed. In order to analyse the available research literature, the Web of Science, Scopus, and PubMed databases were used, in which the search for articles was conducted using terms ("pregnancy," "coronavirus," "SARS-CoV-2," and "newborn") and using PRISMA (Preferred Reporting Items for Systemic Reviews and Meta-Analysis) guidelines for clinical trials. Meta-analyses and systematic reviews (2022-2023) on symptoms, neonatal course, and risk of COVID-19 infection have been summarized. Summary of meta-analyses and systematic reviews (2022-2023) on the effect and adverse reaction of the COVID-19 vaccination is presented.

Results

As a result of the research conducted, it was confirmed that in most pregnant women, no serious signs of the infection were observed, although isolated cases of death related to COVID-19 in pregnant women were reported. Several authors called attention to the more severe course of the infection in pregnant women with obesity. It seemed that no vertical transmission from mother to child was occurring. Nevertheless, the information was not clinching. The condition of the neonates born to mothers with COVID-19 was in most cases described as normal; however, some papers reported deaths of infected neonates.

Conclusions

Due to insufficient data, further research is necessary. Further studies and follow-up are recommended, which would make possible an assessment of remote effects of COVID-19 on pregnancy and vital parameters of the newborn.

COVID-19 pandemic and neonatal birth weight: a systematic review and meta-analysis

OBJECTIVES

Lockdown was implemented in many countries during the pandemic, which led to myriad changes in pregnant women's lives. However, the potential impacts of the COVID-19 pandemic on neonatal outcomes remain unclear. We aimed to evaluate the association between the pandemic and neonatal birth weight.

STUDY DESIGN

This was a systematic review and meta-analysis of the previous literature.

METHODS

We searched the MEDLINE and Embase databases up to May 2022 and extracted 36 eligible studies that compared neonatal birth weight between the pandemic and the prepandemic period. The following outcomes were included: mean birth weight, low birth weight (LBW), very low birth weight (VLBW), macrosomia, small for gestational age (SGA), very small for gestational age (VSGA), and large for gestational age (LGA). Statistical heterogeneity among studies was assessed to determine whether a random effects model or fixed effects model was conducted.

RESULTS

Of the 4514 studies identified, 36 articles were eligible for inclusion. A total of 1,883,936 neonates during the pandemic and 4,667,133 neonates during the prepandemic were reported. We identified a significant increase in mean birth weight (pooled mean difference [95% confidence interval (CI)] = 15.06 [10.36, 19.76], I² = 0.0%, 12 studies) and a reduction in VLBW (pooled OR [95% CI] = 0.86 [0.77, 0.97], I² = 55.4%, 12 studies). No overall effect was identified for other outcomes: LBW, macrosomia, SGA, VSGA, and LGA. There was publication bias for mean birth weight with a borderline significance (Egger's P = 0.050).

CONCLUSION

Pooled results showed the pandemic was significantly associated with an increase in mean birth weight and a reduction in VLBW, but not for other outcomes. This review provided clues about the indirect effects of the pandemic on neonatal birth weight and more healthcare measures needed to improve neonatal long-term health.

Comparison of maternal and fetal health outcomes in the pandemic period of covid-19 with the same last year duration in health centers of second largest city of Iran: A population-based cohort study

Objective

The exact link between COVID-19 pandemic and different adverse outcomes of pregnancy remains unclear. Plus, large-scale research is lacking. In the present study, we aimed to compare the maternal and fetal health outcomes during the COVID-19 pandemic with the same last year duration in Iran.

Design

Two retrospective cohorts (pre-COVID-19 and during COVID-19) were studied. The pre-COVID-19 cohort include pregnant women who had given birth between January 1, 2019 and December 31, 2019. The COVID-19 cohort, who had given birth between January 1, 2020 and December 31, 2020. The characteristics of pregnant women before COVID-19 and during COVID-19 pandemic were compared with Fisher's exact test. Univariate and multivariate log-binomial regression models were used to determine the risk ratios of the impacts of the COVID-19 pandemic on adverse pregnancy outcomes.

Results

Among 128968 women showed that women who had given birth during the pandemic were more likely to be of young age, lower rates of alcohol consumption and smoking, lower weight gain, and higher rates of using synthetic milk for feeding neonates (P < 0.05). Also, the risks of preterm labor were high (cOR 95% CI, 1.13 to 1.31; p < 0.01) and the risk of caesarian were low (cOR 95% CI, 0.95 0.92 to 0.98; p < 0.01) among pregnant women who gave birth during the COVID-19 pandemic compared with those who gave birth before the pandemic.

Conclusions

In summary, we found that during the COVID-19 pandemic there were the higher risks of preterm labor and lower risk of caesarean among pregnant women.

PREGNANT WOMEN WITH COVID-19 AND PLACENTA ANGIOGENESIS

OBJECTIVE

Aim of our research was to conduct a clinical and laboratory analysis of the impact of COVID-19 on pregnancy and the condition of the fetus.

PATIENTS AND METHODS

Materials and Methods: At the first stage, we conducted a retrospective examination of 50 pregnant women treated at Ternopil Municipal Hospital No.2 (Ukraine) between November 2020 and January 2022 with the history of COVID-19, confirmed by PCR test, and 25 pregnant COVID-19 negative pregnant women (control group). At the second stage, we performed prospective cohort study and involved 40 pregnant women treated with the history of COVID-19, confirmed by PCR, and 10 pregnant COVID-19 negative women with a physiological course of pregnancy as a control group.Women were divided into the following groups: group I -10 women diagnosed with COVID-19 during the first trimester of pregnancy: group II-15 women diagnosed during the second trimester; group III-15 women diagnosed during the third trimester. Ultrasound examination and cardiotocograms were performed to assess fetus status. Blood samples were collected at delivery. To determine whether COVID-19 could alter placental angiogenesis, vascular endothelial growth factor A (VEGFA), PlGF and interleuin-32-α were assessed.

RESULTS

Results: We identified that concentration of VEGFA was 95.30±5.65 pg/ml in control group. In women who had COVID-19 in first trimester, this index was 1.3 times higher, in second trimester 1.63 times higher and in third trimester by 2 times compared to control group. PlGF concentration was only 27,4 percent in group I, 16 percent in group II and 30 percent in group III,compared to control group. Concentration of interleuin-32-α was 67.27±5.63 pg/ml in control group and increased to 167 percent in group I, by 2.8 times in group II and by 6.3 times in group III compared to control group.

CONCLUSION

Conclusions: COVID-19 has a negative impact on placental angiogenesis, including VEGFA and PlGF. Fetal post-COVID-19 syndrome requires timely diagnosis of disorders and further study. Post-COVID-19 syndrome is an immune-dependent pathology in which the processes of protracted cytokine activation occur in the body of a pregnant woman.

Impacts of COVID-19 pandemic on preterm birth: a systematic review and meta-analysis

OBJECTIVES

The COVID-19 pandemic has significantly affected healthcare systems and daily well-being. However, the reports of the indirect impacts of the pandemic on preterm birth remain conflicting. We performed a meta-analysis to examine whether the pandemic altered the risk of preterm birth.

STUDY DESIGN

This was a systematic review and meta-analysis of the previous literature.

METHODS

We searched MEDLINE and Embase databases until March 2022 using appropriate keywords and extracted 63 eligible studies that compared preterm between the COVID-19 pandemic period and the prepandemic period. A random effects model was used to obtain the pooled odds of each outcome. The study protocol was registered with PROSPERO (No. CRD42022326717).

RESULTS

The search identified 3827 studies, of which 63 reports were included. A total of 3,220,370 pregnancies during the COVID-19 pandemic period and 6,122,615 pregnancies during the prepandemic period were studied. Compared with the prepandemic period, we identified a significant decreased odds of preterm birth (PTB; <37 weeks' gestation; pooled odds ratio [OR; 95% confidence interval (CI)] = 0.96 [0.94, 0.98]; I² = 78.7%; 62 studies) and extremely PTB (<28 weeks' gestation; pooled OR [95% CI] = 0.92 [0.87, 0.97]; I² = 26.4%; 25 studies) during the pandemic, whereas there was only a borderline significant reduction in the odds of very PTB (<32 weeks' gestation; pooled OR [95% CI] = 0.93 [0.86, 1.01]; I² = 90.1%; 33 studies) between the two periods. There was significant publication bias for PTB.

CONCLUSION

Pooled results suggested the COVID-19 pandemic was associated with preterm birth, although there was only a borderline significant reduction for very PTB during the pandemic compared with the prepandemic period. Large studies showed conflicting results, and further research on whether the change is related to pandemic mitigation measures was warranted.

Mild COVID-19 Was Not Associated with Impaired IVF Outcomes or Early Pregnancy Loss in IVF Patients

Data collection regarding the effects of COVID-19 on reproduction is ongoing. This study examined the effect of COVID-19 on IVF cycle parameters and early pregnancy outcomes. It included two arms: the first compared non-exposed cycles to post-SARS-CoV-2 IVF cycles. Sperm parameters were also compared. The second, prospective arm compared pregnancy outcomes among IVF patients who contracted COVID-19 during early pregnancy to those who did not. None of the patients were vaccinated against SARS-CoV-2. The first arm included 60 treatment cycles of women with confirmed COVID-19, compared to 60 non-exposed cycles (either the same patient before exposure or matched non-exposed patients). The outcomes of the treatment cycles did not differ significantly between exposed and non-exposed groups, including number of oocytes, endometrial thickness, fertilization rate and number of top-quality embryos. In 11 cycles, the male partner had also recently recovered: sperm concentration was lower post-exposure: 6.27 million/mL vs. 16.5 pre-exposure (p = 0.008). In 189 patients with IVF-achieved pregnancies, pregnancy loss and hospital admissions did not differ between exposed and non-exposed groups. IVF treatment outcomes and the rate of early pregnancy loss appears to be unaffected by SARS-CoV-2 disease, despite a minor decline in sperm concentration among recent recoverees.