Association between vomiting in the first trimester and preterm birth: a retrospective birth cohort study in Wuhan, China

Evaluation of nausea and vomiting in the first trimester on the risk of adverse birth outcomes and the contribution of genetic polymorphisms: a pilot prospective study

PURPOSE

To evaluate the impact of Nausea and Vomiting in Pregnancy (NVP) on the risk of Preterm Birth (PTB) and Low Birth Weight (LBW), and explore the effect of genetic polymorphisms on the severity of NVP.

METHODS

A prospective study was conducted. Participants' experience of NVP prior to 12 gestational weeks were evaluated by a Pregnancy-Unique Quantification of Emesis and Nausea (PUQE) scale. 11 Single Nucleotide Polymorphisms (SNPs) loci located in growth differentiation factor 15 (GDF15) and leucine-rich repeat containing 25 (LRRC25) gene of chr19p13.11 and intergenic region of chr4q12 were genotyped, which were implicated as genetic risk factors for NVP. Logistic regression models were applied to determine the effect of NVP in the first trimester on the risk of PTB and LBW, and genetic polymorphisms on the risk of NVP.

RESULTS

Among 413 pregnant women, the incidence of nausea and vomiting was 85.5% (n = 353) in the first trimester, including 38.7% (n = 160) mild vomiting, 42.6% (n = 176) moderate vomiting and 4.1% (n = 17) severe vomiting. 33 were PTB, 20 were LBW. Compared with pregnant women without NVP, women with mild, moderate or severe NVP in the first trimester were not associated with the risk of PTB and LBW. Besides, the polymorphisms of 11 SNPs loci were not associated with the risk of NVP.

CONCLUSIONS

Our study indicated that symptoms of nausea and vomiting in the first trimester were not significantly associated with PTB and LBW, and there were also no associations between GDF15 and LRRC25 polymorphisms and NVP.

Preterm delivery rate in China: a systematic review and meta-analysis

BACKGROUND

Preterm delivery rate is a crucial public health indicator, yet reliable statistic is currently not available in China. In this systematic review and meta-analysis, we aimed to review studies on preterm delivery rate in China, explore sources of heterogeneity, and estimate the preterm delivery rate in China.

METHODS

Published studies on preterm delivery rate in China since 2010 were electronically searched from PubMed, Embase, Web of Science, China National Knowledge Infrastructure, China Science and Technology Journal Database, and Wanfang Database, and complemented by manual search. Study selection, data extraction, and quality and bias assessment (using the Joanna Briggs Institute Critical Appraisal Checklist) were conducted by two reviewers independently. Random-effects meta-analysis was performed to estimate the pooled preterm delivery rate, and prespecified stratified analysis was conducted to explore sources of heterogeneity.

RESULTS

The database search returned 4494 articles and manual search identified 10 additional studies. In total, 162 studies were eligible, of which 124 were hospital-based and 38 population-based. The pooled preterm delivery rate of hospital-based studies (7.2%; 95% CI: 6.9% to 7.6%) was significantly higher than that of population-based studies (4.9%; 95% CI: 4.5% to 5.4%) (P for subgroup difference < 0.001). Among population-based studies, the rate tended to differ by geography (P for subgroup difference = 0.07): 5.3% for Eastern, 4.6% for Central, and 3.8% for Western.

CONCLUSIONS

According to population-based studies, the preterm delivery rate in China is around 5%. This rate is substantially lower than estimates from hospital-based studies or estimates from a combination of both hospital-based and population-based studies as having been done in previous studies.

Preterm delivery rate in China: a systematic review and meta-analysis

BACKGROUND

Preterm delivery rate is a crucial public health indicator, yet reliable statistic is currently not available in China. In this systematic review and meta-analysis, we aimed to review studies on preterm delivery rate in China, explore sources of heterogeneity, and estimate the preterm delivery rate in China.

METHODS

Published studies on preterm delivery rate in China since 2010 were electronically searched from PubMed, Embase, Web of Science, China National Knowledge Infrastructure, China Science and Technology Journal Database, and Wanfang Database, and complemented by manual search. Study selection, data extraction, and quality and bias assessment (using the Joanna Briggs Institute Critical Appraisal Checklist) were conducted by two reviewers independently. Random-effects meta-analysis was performed to estimate the pooled preterm delivery rate, and prespecified stratified analysis was conducted to explore sources of heterogeneity.

RESULTS

The database search returned 4494 articles and manual search identified 10 additional studies. In total, 162 studies were eligible, of which 124 were hospital-based and 38 population-based. The pooled preterm delivery rate of hospital-based studies (7.2%; 95% CI: 6.9% to 7.6%) was significantly higher than that of population-based studies (4.9%; 95% CI: 4.5% to 5.4%) (P for subgroup difference < 0.001). Among population-based studies, the rate tended to differ by geography (P for subgroup difference = 0.07): 5.3% for Eastern, 4.6% for Central, and 3.8% for Western.

CONCLUSIONS

According to population-based studies, the preterm delivery rate in China is around 5%. This rate is substantially lower than estimates from hospital-based studies or estimates from a combination of both hospital-based and population-based studies as having been done in previous studies.

Association between maternal outdoor physical exercise and the risk of preterm birth: a case-control study in Wuhan, China

BACKGROUND

China had the second largest proportion of preterm birth (PTB) internationally. However, only 11% of pregnant women in China meet international guidelines for maternal physical activity, a significantly lower proportion than that in Western countries. This study aims to examine the association between outdoor physical exercise during pregnancy and PTB among Chinese women in Wuhan, China.

METHODS

A case-control study was conducted among 6656 pregnant women (2393 cases and 4263 controls) in Wuhan, China from June 2011 to June 2013. Self-reported measures of maternal physical exercise (frequency per week and per day in minutes) were collected. Adjusted odds ratios were estimated using Bayesian hierarchical logistic regression and a generalized additive mixed model (GAMM).

RESULTS

Compared to women not involved in any physical activity, those who participated in physical exercise 1-2 times, 3-4 times, and over five times per week had 20% (aOR: 0.80, 95% credible interval [95% CI]: 0.68-0.92), 30% (aOR: 0.70, 95% CI: 0.60-0.82), and 32% (aOR: 0.68, 95% CI: 0.59-0.78) lower odds of PTB, respectively. The Bayesian GAMM showed that increasing physical exercise per day was associated with lower risk of PTB when exercise was less than 150 min per day; however, this direction of association is reversed when physical exercise was more than 150 min per day.

CONCLUSION

Maternal physical exercise, at a moderate amount and intensity, is associated with lower PTB risk. More data from pregnant women with high participation in physical exercise are needed to confirm the reported U-shape association between the physical exercise and risk of preterm birth.

Severity of nausea and vomiting in pregnancy and early childhood neurobehavioural outcomes: The Growing Up in Singapore Towards Healthy Outcomes study

BACKGROUND

Nausea and vomiting of pregnancy (NVP) affects 50 to 80 per cent of women. The existing literature has examined NVP from the perspective of the mother, and relatively less is known about offspring outcomes.

OBJECTIVES

To study the relationships of NVP with social-emotional, behavioural, and cognitive outcomes of the offspring in a multi-ethnic Asian cohort.

METHODS

In the Growing Up in Singapore Towards Healthy Outcomes prospective mother-offspring cohort study, mothers responded to a structured NVP questionnaire at 26-28 weeks' gestation (n = 1172) and participants with severe NVP were confirmed using medical records. Children underwent multiple neurodevelopmental assessments throughout childhood. We conducted multivariable regressions with post-estimation predictive margins to understand the associations of NVP with offspring neurobehavioural outcomes, which included 1-year Infant-Toddler Social and Emotional Assessment, 1.5-year Quantitative Checklist for Autism in Toddlers, 2-year Bayley Scales of Infant and Toddler Development, 2- and 4-year Child Behavior Checklist, and 4.5-year Kaufman Brief Intelligence Test. Analyses were adjusted for household income, birth variables, maternal mental health, and other relevant medical variables. Cohen's d effect sizes were calculated using standardised mean differences (μ_d ).

RESULTS

Mothers were categorised into no (n = 296, 25.3%), mild-moderate (n = 686, 58.5%), and severe NVP (n = 190, 16.2%), of whom 67 (5.7%) required admission. Compared to children of mothers who had no or mild-moderate NVP, children with exposure to severe NVP exhibited more externalising behaviours (μ_d 2.0, 95% CI 0.3, 3.6; Cohen's d = 0.33) and social communication difficulties before 2 years (μ_d 4.1, 95% Cl 0.1, 8.0; Cohen's d = 0.38), both externalising (μ_d 1.5, 95% CI 0.4, 2.6; Cohen's d = 0.43) and internalising behaviours at 2 years (μ_d 1.2, 95% CI 0.1, 2.2; Cohen's d = 0.35), and only internalising behaviours after 2 years (μ_d 1.1, 95% CI 0.4, 2.0; Cohen's d = 0.37).

CONCLUSIONS

Severe NVP is highly prevalent in this Asian cohort and may be adversely associated with multiple offspring neurobehavioural outcomes.

Incidence and trend of preterm birth in China, 1990-2016: a systematic review and meta-analysis

OBJECTIVES

To update the WHO estimate of preterm birth rate in China in 1990-2016 and to further explore variations by geographic regions and years of occurrence.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

Pubmed, Embase, Cochrane Library and Sinomed databases were searched from 1990 to 2018.

ELIGIBILITY CRITERIA

Studies were included if they provided preterm birth data with at least 500 total births. Reviews, case-control studies, intervention studies and studies with insufficient information or published before 1990 were excluded. We estimated pooled incidence of preterm birth by a random effects model, and preterm birth rate in different year, region and by livebirths or all births in subgroup analyses.

RESULTS

Our search identified 3945 records. After the removal of duplicates and screening of titles and abstracts, we reviewed 254 studies in full text and excluded 182, leaving 72 new studies. They were combined with the 82 studies included in the WHO report (154 studies, 187 data sets in total for the meta-analysis), including 24 039 084 births from 1990 to 2016. The pooled incidence of preterm birth in China was 6.09% (95% CI 5.86% to 6.31%) but has been steadily increasing from 5.36% (95% CI 4.89% to 5.84%) in 1990-1994 to 7.04% (95% CI 6.09% to 7.99%) in 2015-2016. The annual rate of increase was about 1.05% (95% CI 0.85% to 1.21%). Northwest China appeared to have the highest preterm birth rate (7.3%, 95% CI 4.92% to 9.68% from 1990 to 2016).

CONCLUSIONS

The incidence of preterm birth in China has been rising gradually in the past three decades. It was 7% in 2016. Preterm birth rate varied by region with the West having the highest occurrence.

Nausea, vomiting and poor appetite during pregnancy and adverse birth outcomes in rural Nepal: an observational cohort study

Background

Nausea and vomiting are experienced by a majority of pregnant women worldwide. Previous studies have yielded conflicting results regarding their impact on birth outcomes and few studies have examined this relationship in settings with limited resources. We aimed to determine the effect of nausea, vomiting and poor appetite during pregnancy on birth outcomes in rural Nepal.

Methods

Observational cohort study using data collected in two randomized, community-based trials to assess the effect of influenza immunization during pregnancy on reproductive and respiratory outcomes among pregnant women and their offspring. Pregnant women in Sarlahi District, Nepal were recruited from 2011 to 2013. Exposure was defined as nausea, vomiting or poor appetite at any point during pregnancy and by trimester; symptoms were recorded monthly throughout pregnancy. Adverse outcomes were low birth weight (LBW), preterm birth and small for gestational age (SGA). Adjusted relative risks (aRR) with 95% CIs are reported from Poisson regressions with robust variance.

Results

Among 3,623 pregnant women, the cumulative incidence of nausea, vomiting or poor appetite was 49.5% (n = 1793) throughout pregnancy and 60.6% (n = 731) in the first trimester. Significantly higher aRRs of LBW and SGA were observed among women experiencing symptoms during pregnancy as compared to symptom free women (LBW: aRR 1.20; 95% CI 1.05 1.28; SGA: aRR 1.16; 95% CI 1.05 1.28). Symptoms in the first trimester were not significantly associated with any of the outcomes. In the second trimester, we observed significantly higher aRRs for LBW and SGA (LBW: aRR 1.17; 95% CI 1.01 1.36; SGA: aRR 1.16; 95% CI 1.05 1.29) and a significantly lower aRR for preterm birth (aRR 0.75; 95% CI 0.59 0.96). In the third trimester, we observed significantly higher aRRs for LBW and SGA (LBW: aRR 1.20; 95% CI 1.01 1.43; SGA: aRR 1.14; 95% CI 1.01 1.29).

Conclusions

Symptoms of nausea, vomiting or poor appetite during pregnancy are associated with LBW, SGA and preterm birth in a setting with limited resources, especially beyond the first trimester.

Trial registration

Prospectively registered at ClinicalTrials.gov on Dec 17, 2009 (NCT01034254).