Calcium Aspirin Multiple Micronutrients (CAMMS) to Reduce Preterm Birth

Inclusion Criteria: * Woman, confirmed pregnant by urinary pregnancy test * 6\<20 weeks' gestation determined by fetal ultrasound exam; * Pregnancy must be intrauterine; multiple fetus pregnancies are eligible. * Women must be willing and able to give informed consent; * willing to receive antenatal visits at one of the study clinics. * In Burkina Faso, women must be willing to take monthly sulfadoxine-pyrimethamine. Exclusion Criteria: * Pregnant women who are currently taking aspirin, calcium, or MMS; * have a history of peptic ulcer or have any other contraindications to any of the study drugs; * have acute or chronic condition that might interfere with the study as judged by the research clinician including severe anemia defined as Hb\<5 g/dL; * have other reasons which, at the study research physician's discretion, mean that receipt of the study drugs or participation in the trial would not be advisable. NOTE: Women who have been started on IFA by MoH or private health care provider but are willing discontinue the IFA dispensed by MoH and to be randomized to IFA or CAMMS will not be excluded.