Efficacy and Adverse Side Effects of Two Forms of Iron in Pregnancy

To address our primary aim of determining the optimal form of iron in prenatal supplements, we seek to answer the following research questions:

1. Does providing a more bioavailable form of iron (24 mg elemental iron as ferrous bisglycinate) effectively increase ferritin concentration in maternal venous blood and umbilical cord blood, as compared to the standard 24 mg elemental iron as ferrous fumarate? 2. Does 12 weeks of 24 mg daily oral iron as ferrous fumarate increase biomarkers of potential harm (adverse side effects, gut microbiome composition, gut inflammation) in pregnant individuals, as compared to 24 mg daily oral iron as ferrous bisglycinate?

Pregnant individuals 13-25 weeks gestation will be randomized to one of two trial arms to receive either 24 mg elemental iron as ferrous fumarate or 24 mg elemental iron as ferrous bisglycinate for a minimum of 12 weeks during pregnancy until delivery, with optional continuation until 4-weeks postpartum for breastmilk collection. All participants will also receive the standard form and dose of other critical micronutrients during pregnancy (e.g., folic acid, calcium) through the provision of a prenatal multivitamin (not containing iron).

Interested individuals may undergo the informed consent process anytime prior to 25 weeks gestation. Once an individual indicates that they are interested in participating in the trial, the individual will be assigned a unique study ID and a baseline visit will be scheduled.

The baseline visit will occur between 13-25 weeks gestation and will involve discontinuation of current iron/prenatal vitamin supplementation, review and signing the informed consent form (a scanned copy will be shared with the participant), randomization to an iron group, provision of study supplements, completion of a baseline questionnaire, measurement of weight and height, a small blood draw, and provision of a stool collection kit for at-home stool collection.

The intervention period is a minimum of 12 weeks (from baseline at 13-25 weeks to delivery). Participants will supplement daily with the iron and prenatal multivitamin supplements. Monthly follow-up surveys will be sent to participants via email to check-in and receive updates regarding any changes to medical history or medication use.

The follow-up visit will occur between 35-37 weeks gestation and will involve collecting any remaining supplements (for capsule counts and assessment of adherence), a weight measurement, a small blood draw, provision of at-home stool collection kit, and completion of a short follow-up questionnaire.

Optional continuation of study: After the follow-up visit, participants who are planning to breastfeed will have the option to continue supplementing with the study supplements and provide a prenatal colostrum sample and/or 4-week postpartum breastmilk sample.

• Maternal hemoglobin concentration [Срок оценки: Maternal blood sample collected at baseline (13-25 weeks gestation) and at follow-up (35-37 weeks gestation)]
• Umbilical cord ferritin concentration [Срок оценки: Umbilical cord blood collected at time of delivery]
• Umbilical cord hemoglobin concentration [Срок оценки: Umbilical cord blood collected at time of delivery]
• Placental iron concentration [Срок оценки: Placenta collected at time of delivery]
• Gut microbial analysis [Срок оценки: Stool sample collected at baseline (13-25 weeks gestation) and at follow-up (35-37 weeks gestation)]
• Adverse side effects [Срок оценки: Follow-up (35-37 weeks gestation)]
• Markers of inflammation [Срок оценки: Maternal blood sample collected at baseline (13-25 weeks gestation) and at follow-up (35-37 weeks gestation); umbilical cord blood sample collected at time of delivery]
• Hepcidin concentration [Срок оценки: Maternal blood sample collected at baseline (13-25 weeks gestation) and at follow-up (35-37 weeks gestation); umbilical cord blood sample collected at time of delivery]
• Breastmilk iron stores [Срок оценки: Breastmilk sample collected at 4-weeks postpartum]