{
  "release_id": "c7fb95f1d15a7d13",
  "id": "maternal:mrc-vitamin-study",
  "owner": "maternal",
  "kind": "study",
  "slug": "mrc-vitamin-study",
  "name": "MRC Vitamin Study (1991)",
  "aliases": [
    "MRC Vitamin Study Research Group trial"
  ],
  "atlases": [
    "maternal"
  ],
  "summary_plain": "A large international trial that tested whether folic acid, taken around the time of conception, prevents neural tube defects in women who had already had an affected pregnancy. Women were given at random folic acid, a mixture of seven other vitamins, both, or neither. Fewer pregnancies were affected in the folic acid groups.",
  "summary_technical": "Randomised, double-blind prevention trial with a factorial design at 33 centres in seven countries, reported in 1991. 1817 women at high risk because of a previous affected pregnancy were allocated at random; 1195 had a completed pregnancy in which the fetus or infant was known to have or not have a neural tube defect. 27 of these had a defect, 6 in the folic acid groups and 21 in the two other groups (relative risk 0.28, 95% CI 0.12 to 0.71). The other vitamins showed no significant protective effect (relative risk 0.80, 95% CI 0.32 to 1.72). The PubMed abstract gives no folic acid dose, no registry number and no per-group denominators, so none are recorded. Only the abstract was read.",
  "editorial_state": "draft",
  "last_substantive_edit": "2026-10-14",
  "last_evidence_check": "2026-10-14",
  "next_review_due": null,
  "identifiers": [],
  "navigation": {
    "maternal": {
      "life-stage": [
        "preconception",
        "pregnancy"
      ],
      "care-area": [
        "preconception-health"
      ]
    }
  },
  "payload": {
    "design": "Randomised, double-blind prevention trial with a factorial design: folic acid, a mixture of seven other vitamins (A, D, B1, B2, B6, C and nicotinamide), both, or neither.",
    "drug_phase": null,
    "registry_statuses": [],
    "start_date": null,
    "primary_completion_date": null,
    "completion_date": null,
    "results_first_posted": null,
    "countries": null,
    "care_setting": {
      "description": "33 centres in seven countries; the abstract does not name them or describe the settings.",
      "snapshot": "maternal:pubmed-1677062-2026-10-14"
    },
    "stopped_early": null,
    "enrollment": [
      {
        "count": 1817,
        "basis": "randomized",
        "unit": "women at high risk of a neural tube defect pregnancy",
        "snapshot": "maternal:pubmed-1677062-2026-10-14"
      }
    ],
    "arms": [
      {
        "id": "maternal:mrc-vitamin-study-arm-folic-acid",
        "label": "Folic acid",
        "intervention": "maternal:folic-acid-supplementation",
        "description": "Folic acid alone. The abstract does not give the dose."
      },
      {
        "id": "maternal:mrc-vitamin-study-arm-other-vitamins",
        "label": "Other vitamins",
        "intervention": null,
        "description": "A mixture of seven other vitamins (A, D, B1, B2, B6, C and nicotinamide)."
      },
      {
        "id": "maternal:mrc-vitamin-study-arm-both",
        "label": "Folic acid and other vitamins",
        "intervention": "maternal:folic-acid-supplementation",
        "description": "Folic acid together with the mixture of seven other vitamins."
      },
      {
        "id": "maternal:mrc-vitamin-study-arm-neither",
        "label": "Neither",
        "intervention": null,
        "description": "Neither folic acid nor the other vitamins."
      }
    ],
    "findings": []
  },
  "content_digest": "f18815a72a4e19fd02fe5df90693f4079ab8173bfbbaa5cb0fce42ca7e7268ed",
  "review": {
    "content_digest": "f18815a72a4e19fd02fe5df90693f4079ab8173bfbbaa5cb0fce42ca7e7268ed",
    "current": [],
    "conflicting": [],
    "stale": [],
    "inactive": []
  },
  "claims": [],
  "decisions": [],
  "milestones": [],
  "relationships": {
    "outgoing": [
      {
        "predicate": "investigates",
        "label": "Tests folic acid taken around the time of conception",
        "clinical_claim_not_fact": false,
        "family": "sourced",
        "other_entity_id": "maternal:folic-acid-supplementation",
        "other_entity_in_atlas": true,
        "claim_id": null,
        "evidence": {
          "snapshot_id": "maternal:pubmed-1677062-2026-10-14",
          "locator": "Abstract, sentence 1, fragment 1 of 3"
        },
        "primary": false,
        "role": null,
        "valid_from": null,
        "valid_to": null
      },
      {
        "predicate": "investigates",
        "label": "Counts neural tube defects (anencephaly, spina bifida, encephalocele) in the pregnancies",
        "clinical_claim_not_fact": false,
        "family": "sourced",
        "other_entity_id": "maternal:neural-tube-defects",
        "other_entity_in_atlas": true,
        "claim_id": null,
        "evidence": {
          "snapshot_id": "maternal:pubmed-1677062-2026-10-14",
          "locator": "Abstract, sentence 1, fragment 3 of 3"
        },
        "primary": false,
        "role": null,
        "valid_from": null,
        "valid_to": null
      }
    ],
    "incoming": []
  },
  "page_path": "studies/mrc-vitamin-study/",
  "context_path": "api/v1/context/maternal--mrc-vitamin-study.md"
}