Short interpregnancy intervals, maternal folate levels, and infants born small for gestational age: a preliminary study in a Canadian supplement-using population

Short interpregnancy interval can lead to adverse pregnancy outcomes: A meta-analysis

BACKGROUND

The evidence of some previous papers was insufficient in studying the causal association between interpregnancy interval (IPI) and adverse pregnancy outcomes. In addition, more literature have been updated worldwide during the last 10 years.

METHODS

English and Chinese articles published from January 1980 to August 2021 in the databases of PubMed, Cochrane Library, Ovid, Embase, China Biology Medicine disc (CBM), and China National Knowledge Infrastructure (CNKI) were searched. Then following the inclusion and exclusion criteria, we screened the articles. Utilizing the Newcastle-Ottawa Scale (NOS), we evaluated the quality of the included articles. The literature information extraction table was set up in Excel, and the meta-analysis was performed with Stata 16.0 software (Texas, USA).

RESULTS

A total of 41 articles were included in the meta-analysis, and NOS scores were four to eight. The short IPI after delivery was the risk factor of preterm birth (pooled odds ratio 1.49, 95% confidence interval 1.42-1.57), very preterm birth (pooled OR: 1.82, 95% CI: 1.55-2.14), low birth weight (pooled OR: 1.33, 95% CI: 1.24-1.43), and small for gestational age (pooled OR: 1.14, 95% CI: 1.07-1.21), offspring death (pooled OR: 1.60, 95% CI: 1.51-1.69), NICU (pooled OR: 1.26, 95% CI: 1.01-1.57), and congenital abnormality (pooled OR: 1.10, 95% CI: 1.05-1.16), while was not the risk factor of gestational hypertension (pooled OR: 0.95, 95% CI: 0.93-0.98) or gestational diabetes (pooled OR: 1.06, 95% CI: 0.93-1.20).

CONCLUSION

Short IPI (IPI < 6 months) can lead to adverse perinatal outcomes, while it is not a risk factor for gestational diabetes and gestational hypertension. Therefore, more high-quality studies covering more comprehensive indicators of maternal and perinatal pregnancy outcomes are needed to ameliorate the pregnancy policy for women of childbearing age.

A New Birthweight Reference by Gestational Age: A Population Study Based on the Generalized Additive Model for Location, Scale, and Shape Method

BACKGROUND

It is important to choose a suitable birthweight reference to assess newborns, especially those that are small for gestational age (SGA). Currently, there is no regional standard reference for the north of China or for Shandong province.

METHODS

A total of 130,911 data records of singleton, live neonates born at 24-42 weeks of gestation were collected from 2016 to 2018 in Shandong province. A new birthweight-for-gestational age percentile reference was constructed based on the Generalized Additive Model for Location, Scale and Shape (GAMLSS) package in R version 3.5. The established gestational age weight curve was compared separately with the Fenton curve, INTERGROWTH-21st curve, and the Chinese Neonatal Network Standard curve of 2015.

RESULTS

We established the reference values of birthweight by gestational age at the 3rd, 10th, 25th, 50th, 75th, 90th, and 97th percentiles. Newborns had much heavier birthweights than those in the INTERGROWTH-21st and Fenton curves at most gestational ages. Although the newborns' birthweight references were closer to the Chinese Neonatal Network Standard except a few for gestational age, this study and INTERGROWTH-21st had similar birthweight curve shapes.

CONCLUSIONS

There are obvious differences among the criteria for newborn birthweights. Therefore, it is more accurate to assess newborns using the local birthweight reference.

Folate Levels by Time Since Last Live Birth Among U.S. Women, 2007-2016

Background: Folate depletion in the postpartum period may increase the risk of adverse pregnancy outcomes for women with a short interpregnancy interval following a live birth. We sought to examine folate levels by time since last live birth among U.S. women. Materials and Methods: Data were from 4,809 U.S. women, 20-44 years of age, participating in the National Health and Nutrition Examination Survey, 2007-2016. Red blood cell (RBC) folate was measured using microbiological assay on whole blood samples. Dietary folate intake and folic acid supplementation were measured during a 24-hour dietary recall. Prevalence of supplementation by time since last live birth was estimated from logistic regression models; mean levels of RBC folate and mean intake of dietary folate equivalent were estimated from linear regression models. Models were adjusted for maternal sociodemographic characteristics. Results: In adjusted models, supplementation (±standard error) was highest among women in the first year postpartum (31.7% ± 3.2) compared with nulliparous women (23.7% ± 1.9) and those 2-3 years (15.6% ± 1.9) and ≥3 years (18.4% ± 1.6) after last live birth. Mean RBC folate was highest among women in the first year postpartum, regardless of supplementation, with overall mean levels of 606 ± 15 ng/mL, compared with 484 ± 9, 477 ± 11, and 474 ± 7 among women in the aforementioned groups, respectively. Mean dietary folate intake was also highest among postpartum women: 542 ± 23 mcg/day, compared with 474 ± 12, 486 ± 21, and 467 ± 12. Conclusions: Folate levels are highest in the first year postpartum compared with other time periods within a woman's reproductive lifespan. These findings do not support the idea that postpartum U.S. women are depleted in folate, on average.