Baseline characteristics
| . | Daily (n = 98) . | Alternate (n = 99) . | Three times a week (n = 103) . | Total (N = 300) . |
|---|---|---|---|---|
| Age (y) | 31 (27-35) | 31 (27-35) | 30 (27-34) | 30.5 (27-34) |
| Socioeconomic status∗ (quintile) | ||||
| 1 (most deprived) | 20 (34.5) | 18 (28.1) | 16 (22.9) | 54 (28.1) |
| 2 | 11 (19.0) | 17 (26.6) | 29 (41.4) | 57 (29.7) |
| 3 | 8 (13.8) | 9 (14.1) | 8 (11.4) | 25 (13.0) |
| 4 | 11 (19.0) | 11 (17.2) | 9 (12.9) | 31 (16.1) |
| 5 (least deprived) | 8 (13.8) | 9 (14.1) | 8 (11.4) | 25 (13.0) |
| Gestation (wk) | 12.7 (12.1-13.1) | 12.7 (12.3-13.1) | 12.7 (12.3-13.1) | 12.7 (12.3-13.1) |
| Ethnicity | ||||
| White | 85 (86.7) | 83 (83.8) | 91 (88.3) | 259 (86.3) |
| Mixed | 1 (1.0) | 0 (0.0) | 3 (2.9) | 4 (1.3) |
| Asian or Asian British | 9 (9.2) | 13 (13.1) | 5 (4.9) | 27 (9.0) |
| Black, African, Caribbean, Black British | 2 (2.0) | 3 (3.0) | 3 (2.9) | 8 (2.7) |
| Other | 1 (1.0) | 0 (0.0) | 1 (1.0) | 2 (0.7) |
| Smoker | 13 (13.3) | 5 (5.1) | 6 (5.8) | 24 (8.0) |
| Height (cm) | 164 (160-168) | 165 (159-169) | 163 (160-170) | 164 (160-169) |
| Weight (kg) | 70 (61-83) | 70 (62-85) | 74.4 (62.7-84.7) | 70.5 (62-84) |
| BMI (kg/m2) | 25.7 (22.9-31.2) | 26.5 (23-31.6) | 27.3 (23.5-31.2) | 26.5 (23.1-31.2) |
| Parity | 1 (0-1) | 1 (0-1) | 1 (0-1) | 1 (0-1) |
| Hb (g/L) | 130 (124-135) | 129 (126-135) | 132 (124-138) | 130 (125-136) |
| Iron-containing supplements being taken at baseline† | 22 (22.9) | 24 (26.7) | 17 (17.7) | 63 (22.3) |
| Known hemoglobinopathy trait | 3 (3.1) | 4 (4.0) | 4 (3.9) | 11 (3.7) |
| Previous anemia | ||||
| Outside of pregnancy | 12 (12.2) | 6 (6.1) | 12 (11.7) | 30 (10.0) |
| During pregnancy | 5 (5.1) | 7 (7.1) | 10 (9.7) | 22 (7.3) |
| Both | 0 (0.0) | 1 (1.0) | 1 (1.0) | 2 (0.7) |
| Comorbidity‡ | 9 (9.2) | 11 (11.1) | 18 (17.5) | 38 (12.7) |
| At least 1 previous termination | 12 (12.2) | 13 (13.1) | 14 (13.6) | 39 (13.0) |
| At least 1 previous miscarriage or still birth | 30 (30.6) | 27 (27.3) | 32 (31.1) | 89 (29.7) |
| At least 1 previous postpartum hemorrhage (>1/L) | 3 (3.1) | 7 (7.1) | 11 (10.7) | 21 (7.0) |
| . | Daily (n = 98) . | Alternate (n = 99) . | Three times a week (n = 103) . | Total (N = 300) . |
|---|---|---|---|---|
| Age (y) | 31 (27-35) | 31 (27-35) | 30 (27-34) | 30.5 (27-34) |
| Socioeconomic status∗ (quintile) | ||||
| 1 (most deprived) | 20 (34.5) | 18 (28.1) | 16 (22.9) | 54 (28.1) |
| 2 | 11 (19.0) | 17 (26.6) | 29 (41.4) | 57 (29.7) |
| 3 | 8 (13.8) | 9 (14.1) | 8 (11.4) | 25 (13.0) |
| 4 | 11 (19.0) | 11 (17.2) | 9 (12.9) | 31 (16.1) |
| 5 (least deprived) | 8 (13.8) | 9 (14.1) | 8 (11.4) | 25 (13.0) |
| Gestation (wk) | 12.7 (12.1-13.1) | 12.7 (12.3-13.1) | 12.7 (12.3-13.1) | 12.7 (12.3-13.1) |
| Ethnicity | ||||
| White | 85 (86.7) | 83 (83.8) | 91 (88.3) | 259 (86.3) |
| Mixed | 1 (1.0) | 0 (0.0) | 3 (2.9) | 4 (1.3) |
| Asian or Asian British | 9 (9.2) | 13 (13.1) | 5 (4.9) | 27 (9.0) |
| Black, African, Caribbean, Black British | 2 (2.0) | 3 (3.0) | 3 (2.9) | 8 (2.7) |
| Other | 1 (1.0) | 0 (0.0) | 1 (1.0) | 2 (0.7) |
| Smoker | 13 (13.3) | 5 (5.1) | 6 (5.8) | 24 (8.0) |
| Height (cm) | 164 (160-168) | 165 (159-169) | 163 (160-170) | 164 (160-169) |
| Weight (kg) | 70 (61-83) | 70 (62-85) | 74.4 (62.7-84.7) | 70.5 (62-84) |
| BMI (kg/m2) | 25.7 (22.9-31.2) | 26.5 (23-31.6) | 27.3 (23.5-31.2) | 26.5 (23.1-31.2) |
| Parity | 1 (0-1) | 1 (0-1) | 1 (0-1) | 1 (0-1) |
| Hb (g/L) | 130 (124-135) | 129 (126-135) | 132 (124-138) | 130 (125-136) |
| Iron-containing supplements being taken at baseline† | 22 (22.9) | 24 (26.7) | 17 (17.7) | 63 (22.3) |
| Known hemoglobinopathy trait | 3 (3.1) | 4 (4.0) | 4 (3.9) | 11 (3.7) |
| Previous anemia | ||||
| Outside of pregnancy | 12 (12.2) | 6 (6.1) | 12 (11.7) | 30 (10.0) |
| During pregnancy | 5 (5.1) | 7 (7.1) | 10 (9.7) | 22 (7.3) |
| Both | 0 (0.0) | 1 (1.0) | 1 (1.0) | 2 (0.7) |
| Comorbidity‡ | 9 (9.2) | 11 (11.1) | 18 (17.5) | 38 (12.7) |
| At least 1 previous termination | 12 (12.2) | 13 (13.1) | 14 (13.6) | 39 (13.0) |
| At least 1 previous miscarriage or still birth | 30 (30.6) | 27 (27.3) | 32 (31.1) | 89 (29.7) |
| At least 1 previous postpartum hemorrhage (>1/L) | 3 (3.1) | 7 (7.1) | 11 (10.7) | 21 (7.0) |
BMI, body mass index, Q, quartile.
Estimated using the participant’s postcode to determine their Index of Multiple Deprivation (IMD) (2019). IMD data were not recorded for 108 participants because consent was not obtained to collect their postcode.
There were 17 participants for whom baseline medication was indicated but it is unknown whether it contained iron. In total, of those who took iron supplements at baseline, 41 (65%) were still taking them at the end of the study.
Including hypertension, cardiac disease, thyroid disorders, renal disease, preexisting diabetes, clotting disorders, and anticoagulant therapy. There were 2 missing Hb values for participants at the baseline assessment. The data are presented as number (percentage) for categorical variables and median (Q1-Q3) for continuous variables.