INTRODUCTION
Managing adequate intakes of calcium during pregnancy is important in
several physiological processes, and reduces the risk of perinatal
adverse events such as hypertensive disorders and preterm birth. (1-3)
The recommended daily intake (RDI) of calcium is 1000 mg/day for all
women of childbearing age. (1) Calcium demands increase substantially
during pregnancy, but are met by an increased intestinal absorption,
renal reabsorption and mobilization from the maternal skeleton, mediated
mostly by an increase in PTH and IGF-I over the course of pregnancy.
(4-6) However, these measures are insufficient to compensate for an
inadequate intake. Adult women of childbearing age (18-50) have
remarkably low intakes of calcium. 22.7-44.5% of women in the
Netherlands consume less than the estimated average requirement (EAR) of
750 mg/day. (7) In the UK, 6-8% of women of childbearing age consume
even less than the lower reference nutrient intake (LRNI) of 400mg/day.
(8) Individuals habitually consuming less than the LRNI are almost
certainly deficient of the nutrient concerned. (9) The EAR and
recommended daily intake (RDI) are further explained in the supplement.
Calcium supplementation starting from the second or third trimester in
women with chronically low intakes reduces risks of gestational
hypertension and preeclampsia, with estimated risk reductions of 30%
and 50%, respectively. (2, 3, 10) The WHO and Dutch guidelines for
pregnancy consultation therefore recommend daily calcium supplementation
starting from the 20th week of gestation in women with
an inadequate intake. (11, 12) Due to tight regulation of serum calcium
levels (2.10-2.55 mmol/L) (13)), there is poor association between
dietary and total calcium serum levels. (5, 14) Hence, nutritional
screening is the only appropriate method to assess calcium intake.
During regular maternal outpatient clinic visits there is neither time
nor expertise for elaborate dietary assessments. A simple screening tool
for calcium intake could offer a solution, and contribute to better care
and prevention through early detection and intervention in women at risk
of having an inadequate intake, and with that the improvement of
perinatal outcomes and maternal-fetal health. A digital screening tool
could also contribute to improved self-management in periconceptional
care, by enabling women to assess and improve their own calcium intake,
and with that leading to greater health care efficiency and maternal and
perinatal outcomes.
To our best knowledge, no studies have been conducted on the development
of a calcium-specific FFQ or a prediction model to assess calcium intake
in pregnancy. We hypothesize that intake of an adequate amount of
calcium can accurately be predicted by a limited number of products.
Therefore, the aim of this study is to develop an effective and simple
digital screening tool based on a prediction model for calcium intake in
pregnancy, that is suitable for making accurate individual predictions
with a minimal number of predictors and can be integrated in existing
pregnancy health platforms (e.g. Smarter Pregnancy) to be used by both
clinicians and women who are or are planning to become pregnant.