Elucidating the Dynamics and Impact of the Gut Microbiome on Maternal Nutritional Status During Pregnancy in Rural Pakistan: Study Protocol for a Prospective, Longitudinal Observational Study
Authors: Wasan Yaqub , Baxter Jo-Anna B. , Spiegel-Feld Carolyn , Begum Kehkashan , Rizvi Arjumand , Iqbal Junaid , Hulst Jessie M. , Bandsma Robert , Suleman Shazeen , Soofi Sajid B. , Parkinson John , Bhutta Zulfiqar A. 
Published: September 2023

Introduction

Undernutrition during pregnancy is linked to adverse pregnancy and birth outcomes and has downstream effects on the growth and development of children. The gut microbiome has a profound influence on the nutritional status of the host. This phenomenon is understudied in settings with a high prevalence of undernutrition, and further investigation is warranted to better understand such interactions.

Methods

This is a prospective, longitudinal observational study to investigate the relationship between prokaryotic and eukaryotic microbes in the gut and their association with maternal BMI, gestational weight gain, and birth and infant outcomes among young mothers (17-24 years) in Matiari District, Pakistan. We aim to enroll 400 pregnant women with low and normal BMIs at the time of recruitment (<16 weeks of gestation).

Analysis

To determine the weight gain during pregnancy, maternal weight is measured in the first and third trimesters. Gut microbiome dynamics (bacterial and eukaryotic) will be assessed using 16S and 18S rDNA surveys applied to the maternal stool samples. Birth outcomes include birthweight, SGA, LGA, preterm birth, and mortality. Infant growth and nutritional parameters include WHO z-scores for weight, length, and head circumference at birth through infancy. To determine the impact of the maternal microbiome, including exposure to pathogens and parasites on the development of the infant microbiome, we will analyze maternal and infant microbiome composition, micronutrients in serum using metallomics (e.g., zinc, magnesium, and selenium), and macronutrients in the stool. Metatranscriptomics metabolomics and markers of inflammation will be selectively deployed on stool samples to see the variations in dietary intake and maternal nutritional status. We will also use animal models to explore the bacterial and eukaryotic components of the microbiome.

Ethics and dissemination

The study is approved by national and institutional ethics boards, and findings will be published in peer-reviewed journals.

Study registration

ClinicalTrials.govIdentifier:NCT05108675.

Strengths and limitations

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The study targets the high fertility age group (17-24) with almost half cohort consisting of low BMI mothers, potentially with an additional risk of adverse pregnancy outcomes, providing an opportunity to comprehend the systematic understanding of the role of microbiota in several pregnancy, birth, and infant outcomes.

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Study investigates both prokaryotic and eukaryotic dynamics of the gut microbiome for in-depth mechanistic insights in a highly malnourished population where contextual evidence is rare.

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Longitudinal design and data collection on a range of exposure indicators and biochemical analysis would enable us to evaluate the association of gut dynamics with several physiological and environmental factors.

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The study follows the STROBE guidelines; however, we expect controlling for all confounding variables may not be possible.

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Focusing on young women, 17-24 years of age, the findings may not be generalizable to younger or older demographics.