Geophagia in pregnancy and its association with nutritional status - A prospective cohort study in rural north-eastern Tanzania

Abstract

Background: Geophagia or soil-eating behavior is common among pregnant women in sub-Saharan Africa, however its relationship with nutritional status demands further investigation. Using a prospective pregnancy cohort from north-eastern Tanzania, we examined the characteristics of geophagia and its association with nutritional status parameters (mid-upper arm circumference (MUAC), vitamin B12, folate, ferritin, and hemoglobin) before conception and throughout the gestational period.

Methods: Pregnant women (n = 530) were interviewed in each trimester regarding their soil-eating habits. Serum concentrations of vitamin B12, folate, ferritin, and hemoglobin, and MUAC were measured before conception and in each trimester. Cross-sectional comparisons between women who ate and did not eat soil were analyzed using Welch's t-test for continuous variables and χ2-test for categorical variables. The association between changes in nutritional status parameters and the initiation of geophagia was investigated using multivariable logistic regression.

Results: The prevalence of geophagia in this cohort was 27% (n = 143) with most women initiating geophagia in the third trimester. Pregnant women that ate soil had significantly lower ferritin (p = 0.001) prior to conception and at concentrations diagnostic of iron deficiency (p = 0.022) compared to women who did not eat soil. Geophagia was associated with lower ferritin (p ≤ 0.001) and lower hemoglobin (p < 0.05) in each trimester and lower folate in the third trimester (p = 0.007). A smaller decline in hemoglobin and folate across the gestational period was associated with reduced odds of initiating geophagia in the third trimester (hemoglobin: OR 0.71, p = 0.008; folate: OR 0.97, p = 0.008). There was no significant association between a change in MUAC, serum B12 or ferritin and the initiation of geophagia during pregnancy.

Conclusions: Prenatal geophagia is closely related to iron and folate status. A greater decrease in hemoglobin and folate is associated with the initiation of geophagia during pregnancy. These findings are particularly relevant to low- and middle-income settings where geophagia is practiced and the prevalence of anemia in pregnancy is high.

Keywords: Anemia; Folate status; Geophagia; Iron status; Mid-upper arm circumference; Pica; Pregnancy; Tanzania; Vitamin B12 status.

Fig. 1

Participant flowchart and inclusion criteria for study analyses. The association between nutritional status parameters and geophagia in each trimester was analyzed cross-sectionally using Welch’s t-test and chi-squared test. The association between the initiation of geophagia in the third trimester and a change in nutritional status from either the first or second trimester was analyzed using multivariable logistic regression

Fig. 2

Diagram of logistic regression analysis model. Predictors were selected using stepwise backward selection from the following list of co-variates: age, parity, maternal occupation, history of miscarriage, gestational age at third trimester visit, enrolment year, supplementation with iron, folate and/or vitamin B12 at enrolment, malaria at any time during pregnancy, use of antihelminth medication at any time during pregnancy, number of scheduled ANC visits during the study, preeclampsia. The change in each nutritional status parameter from first or from second trimester and its association with the initiation of geophagia in the third trimester was tested in separate logistic regression models, adjusting for gestational age at enrolment, civil status and supplementation with iron, folate, and/or B12 at any time during pregnancy

Fig. 3

Trimesters of geophagia occurrence. UpSet plot showing the number of women that reported geophagia in the first, second and/or third trimester among those who completed a dietary recall in all three trimesters and reported geophagia in at least one (n = 103). The set size corresponds to the total number of women with geophagia in a certain trimester. The intersection size corresponds to the number of women with geophagia in one or more trimester(s), with the dots under each column specifying the trimester(s)

Fig. 4

Measurements of nutritional status parameters among women with and without geophagia in each trimester. Data points are means with 95% CIs. Cross-sectional comparisons of nutritional status parameters were analyzed using Welch’s t-test, p-values < 0.05 are shown. Ferritin was corrected for inflammation using a correction factor of 0.67 if CRP > 0.5 mg/L at the time of measurement and log-transformed for statistical analysis. Distributions of the individual datapoints for each group are shaded with sample sizes shown in the bottom corners of each plot

Fig. 5

Proportions of nutritional deficiencies among women with and without geophagia in each trimester. Differences in the distribution of proportions of deficiencies between women who did and did not eat soil in each trimester were analyzed using Pearson’s χ2-test. P-values < 0.05 are shown. Vitamin B12 deficiency was defined as serum B12 < 150pmol/mL, folate deficiency as serum folate < 10nmol/L, iron deficiency as serum ferritin < 15ug/L after using a correction factor of 0.67 if CRP > 5mg/L at the time of measurement, and anemia as < 11g/dL in the first and third trimesters and < 10.5g/dL in the second trimester