Background
Methods
Participants
Measures
Construct | Measurement information and/or exemplar item | Response categories | Participant/timepoint | Source (additional information) |
---|---|---|---|---|
Exposure variable: Maternal alcohol use | Quantity and frequency of maternal alcohol use (standard drink = 10 g of alcohol). | 1. Abstinent: no consumption; 2. Low: ≤7 standard drinks per week, up to 2 standard drinks per occasion; 3. Moderate: ≤7 standard drinks per week, > 2 to ≤4 standard drinks per occasion; 4. Binge: ≤7 standard drinks per week, > 4 standard drinks per occasiona; 5. Heavy: > 7 standard drinks per week; at least weekly or more. | Mother (T1-T3) | O’Leary et al.’s (2010) Prenatal Alcohol Exposure (PAE) categories |
Outcome variable: Infant Gross Motor (GM) Development | Example: Infant can sit upright unsupported. | Standardised GM scaled scores (mean = 10, SD = 3), adjusted for age and prematurity. | Infant (12 M) | Bayley Scales of Infant and Toddler Development - Third edition (BSID-III) [22] |
Background confounder and precision variables: Age at birth | Calculated based on mother/partner and infant date of birth. | ≤ 24 years; 25–29 years; 30–35 years; ≥ 36 years. | Mother, partner (T3/8W) | |
Education | What is your highest level of education? | Less than Year 12; Year 12; Trade certificate, diploma or apprenticeship; Tertiary qualification. | Mother, partner (T3) | |
Birth country | In which country were you born? | Australia; other English-speaking country; non-English-speaking country. | Mother, partner (T3) | |
Single parent household | What is your current marital status? | Single parent household (Yes or No). | Mother (T3) | |
Aboriginal and Torres Strait Islander status | Are you Aboriginal and/or Torres Strait Islander? | Yes or No. | Mother, partner (T3) | |
First language spoken | What was your first language spoken? | English; Language other than English. | Mother, partner (T3) | |
Socio-economic status (SES) | The Socio-Economic Indexes for Areas (SEIFA) data package was used to classify participants into low, moderate or high socio-economic status (SES) deciles based on residential postcode. | Low = deciles 1–3; Moderate = deciles 4–7; High = deciles 8–10. | Mother, partner (T3) | SEIFA data package [45] |
State of residence | State of residence in Australia | New South Wales (NSW) or Western Australia (WA). | Mother (T3) | |
Tobacco in pregnancy | Tobacco use in pregnancy (ever used). | Yes or No. | Mother (T1-T3), partner (T3) | |
Illicit substance in pregnancy | Illicit substance use in pregnancy (ever used). | Yes or No. | Mother (T1-T3), partner (T3) | |
Maternal Depression | In the last 7 days …. I have felt sad or miserable. | Yes most of the time; Yes quite often; Not very often; No not at all. Coded as Normal (scores <9) or Elevated (scores ≤9). | Mother (T1-T3), partner (T3) | Edinburgh Depression Scale (EDS) [26] |
Stress | Over the past week …. I found it hard to wind down. | Not at all; Some degree, or some of the time; Considerable degree, or a good part of the time; Very much, or most of the time. Coded as Normal (scores <10) or Elevated (scores ≤10). | Mother (T1-T3), partner (T3) | Depression, Anxiety and Stress Scales [27] |
Anxiety | Over the past week …. I felt I was close to panic. | Not at all; Some degree, or some of the time; Considerable degree, or a good part of the time; Very much, or most of the time. Coded as Normal (scores <19) or Elevated (scores ≤19). | Mother (T1-T3), partner (T3) | Depression, Anxiety and Stress Scales [27] |
Victim of spousal abuse | My partner insults or shames me in front of others. | Never; Rarely; Occasionally; Frequently; Very Frequently Scores indicating at least moderate severity on the physical or non-physical subscales were combined then binary coded to indicate the presence or absence of abuse (Yes or No). | Mother, partner (T3) | The Index of Spousal Abuse [28] |
Estimated IQ | TOPF scores were converted to provide a valid predictor of the full-scale WAIS-IV IQ [46]. | Low average = ≤84; Average = 85–99; High average = 100–114; Superior = ≥115. | Mother, partner (12 M)b | Test of Premorbid Functioning (TOPF) [29] |
Parity | Total number of pregnancies carried to term prior to the current pregnancy [47]. | 0; 1–2; ≥3. | Mother (T3) | |
Pre-pregnancy body mass index (BMI) | BMI was calculated based on self-reported pre-pregnancy weight and height [48]. | Underweight = < 18.49; Normal weight = 18.50–24.99; Overweight = 25.00–29.99; Obese = ≥30.00 [49]. | Mother, partner (T3) | |
Pregnancy planning | How did you feel about becoming pregnant? | I wanted to become pregnant; I didn’t want to become pregnant; I hadn’t thought about becoming pregnant; Other. Responses were re-coded as pregnancy planned versus not planned; ‘other’ responses were classified based on examination of open-ended responses (n = 69). | Mother (T3) | |
Partner alcohol use | Quantity and frequency of partner alcohol use (standard drink = 10 g of alcohol) | 1. Abstinent: no consumption; 2. Low: ≤7 standard drinks per week, up to 2 standard drinks per occasion; 3. Moderate: < 14 standard drinks per week, > 2 to ≤4 standard drinks per occasion; 4. Binge: ≤14 standard drinks per week, > 4 standard drinks on one occasion; 5. Heavy: > 14 standard drinks per week; at least weekly consumption or more. | Partner (T3) | Australian NHMRC guidelines for drinking among non-pregnant adults were used to classify binge and heavy drinking [50] |
Infant sex | What gender is your baby? | Female; Male. | Mother (8 W) | Extracted from hospital records (Blue Books), as recorded by hospital staff at birth. |
Prematurity | Number of weeks gestation at birth. | Not premature = ≥37 weeks; Premature = ≤36 weeks. | Mother (8 W) | Extracted from hospital records (Blue Books), as recorded by hospital staff at birth. |
Birthweight | Weight in grams at birth, coded into two categories based on Australian norms [51]. | Normal= > 10th percentile for gestational age; Small for gestational age (SGA) = ≤10th percentile for gestational age. | Mother (8 W) | Extracted from hospital records (Blue Books), as recorded by hospital staff at birth. |
Head circumference | Reported in centimetres. | Normal= > 3rd percentile; Small = ≤3rd percentile. | Mother (8 W) | Extracted from hospital records (Blue Books), as recorded by hospital staff at birth. |
Apgar score (5 min) | Post-birth measure of infant health. | Normal = ≥7; Problems at birth = < 7. | Mother (8 W) | Extracted from hospital records (Blue Books), as recorded by hospital staff at birth. |
Alcohol use
Infant GM development
Potential confounders
Planned analyses
Alcohol use category | |||||
---|---|---|---|---|---|
Abstinent | Low (≤7 drinks per week, up to 2 per occasion) | Moderate (≤7 drinks per week, > 2 to ≤4 per occasion) | Binge (≤7 drinks per week, > 4 per occasion) | Heavy (> 7 drinks per week, weekly or more) | |
Trimester 1a (first 6 weeks) | |||||
n (%) | 514 (38.8) | 291 (22.0) | 55 (4.2) | 211 (15.9) | 184 (14.0) |
Drinking days per week, M (SD) | 0 | 1.09 (1.10) | 0.91 (0.60) | 0.98 (0.87) | 3.73 (1.83) |
Typical grams consumed per occasion, M (SD) | 0 | 12.70 (4.11) | 28.31 (4.30) | 38.22 (29.33) | 50.74 (54.01) |
Typical grams consumed per week, M (SD) | 0 | 17.50 (17.70) | 27.50 (18.55) | 30.81 (21.51) | 181.16 (200.02) |
Trimester 1b (second 6 weeks) | |||||
n (%) | 943 (71.2) | 224 (16.9) | 24 (1.8) | 41 (3.1) | 24 (1.8) |
Drinking days per week, M (SD) | 0 | 0.58 (0.63) | 0.66 (0.64) | 0.80 (0.67) | 3.62 (1.80) |
Typical grams consumed per occasion, M (SD) | 0 | 11.13 (4.81) | 29.44 (4.16) | 28.21 (20.07) | 74.36 (121.52) |
Typical grams consumed per week, M (SD) | 0 | 8.32 (9.11) | 18.74 (19.15) | 32.43 (23.56) | 27.18 (43.05) |
Trimester 2 | |||||
n (%) | 894 (67.5) | 339 (25.6) | 37 (2.8) | 14 (1.1) | 13 (1.0) |
Drinking days per week, M (SD) | 0 | 0.70 (0.72) | 0.80 (0.65) | 1.23 (0.90) | 4.40 (2.10) |
Typical grams consumed per occasion, M (SD) | 0 | 12.46 (3.82) | 29.64 (3.45) | 25.14 (14.77) | 58.23 (75.12) |
Typical grams consumed per week, M (SD) | 0 | 9.04 (10.39) | 23.42 (20.28) | 34.39 (21.65) | 189.72 (223.25) |
Trimester 3 | |||||
n (%) | 902 (68.1) | 337 (25.5) | 31 (2.3) | 10 (0.8) | 13 (1.0) |
Drinking days per week, M (SD) | 0 | 1.30 (0.40) | 2.93 (0.32) | 3.30 (16.20) | 2.31 (1.50) |
Typical grams consumed per occasion, M (SD) | 0 | 12.82 (3.60) | 29.27 (3.19) | 32.50 (1.62) | 23.08 (14.51) |
Typical grams consumed per week, M (SD) | 0 | 11.89 (12.90) | 25.38 (18.58) | 29.06 (25.04) | 111.92 (34.97) |
Results
Patterns of alcohol use by mothers across pregnancy
Patterns of alcohol use by partners
Characteristics associated with maternal drinking in pregnancy
Abstainers (n = 452) n (column %) | Drinkers (n = 872) n (column %) | Drinkers vs abstainers - Unadjusted OR (95% CI) | ||
---|---|---|---|---|
Maternal factors | ||||
Age | ≤ 24 | 34 (7.5) | 37 (4.3) | Ref |
25–29 | 112 (24.7) | 162 (18.6) | 1.33 (0.78–2.25) | |
30–35 | 185 (41) | 400 (45.9) | 1.97 (1.2–3.24)** | |
≥ 36 | 121 (26.7) | 273 (31.2) | 2.06 (1.23–3.45)** | |
Level of education | Less than Year 12 | 44 (9.7) | 35 (4.1) | Ref |
Year 12 | 46 (10.2) | 97 (11.1) | 2.61 (1.48–4.61)** | |
Certificate / Diploma | 67 (14.8) | 127 (14.5) | 2.34 (1.37–4)** | |
Bachelor or higher | 295 (65.3) | 613 (70.3) | 2.57 (1.61–4.11)*** | |
Household SES | Low | 38 (8.4) | 22 (2.5) | Ref |
Moderate | 172 (38.1) | 229 (26.3) | 2.29 (1.31–4.02)** | |
High | 242 (53.5) | 621 (71.2) | 4.42 (2.56–7.64)*** | |
State of Residence | New South Wales | 378 (83.8) | 739 (84.7) | Ref |
Western Australia | 73 (16.2) | 134 (15.3) | 0.94 (0.69–1.29) | |
Country of birth | Australia | 248 (54.8) | 512 (58.7) | Ref |
Other English speaking | 50 (11.1) | 194 (22.3) | 1.88 (1.33–2.66)*** | |
NESB | 154 (34.1) | 166 (19) | 0.52 (0.4–0.68)*** | |
Single parent household | No | 412 (91.3) | 825 (94.5) | Ref |
Yes | 39 (8.7) | 48 (5.5) | 0.61 (0.39–0.95)* | |
Aboriginal or Torres Strait Islander | No | 441 (97.6) | 861 (98.7) | Ref |
Yes | 11 (2.4) | 11 (1.3) | 0.53 (0.22–1.24) | |
English first language | No | 166 (36.9) | 174 (20) | Ref |
Yes | 285 (63.1) | 698 (80) | 2.34 (1.77–3.09)*** | |
Tobacco in pregnancy | No | 402 (88.9) | 722 (82.8) | Ref |
Yes | 50 (11.1) | 150 (17.2) | 1.67 (1.18–2.36)** | |
Illicit substances ever in pregnancy | No | 434 (96.2) | 818 (93.7) | Ref |
Yes | 17 (3.8) | 55 (6.3) | 1.68 (0.96–2.95) | |
Depression | Normal | 321 (71.1) | 626 (71.8) | Ref |
Elevated | 130 (28.9) | 246 (28.2) | 0.97 (0.75–1.25) | |
Anxiety | Normal | 328 (72.7) | 679 (77.9) | Ref |
Elevated | 123 (27.3) | 193 (22.1) | 0.76 (0.57–0.99)* | |
Stress | Normal | 377 (83.5) | 711 (81.5) | Ref |
Elevated | 75 (16.5) | 161 (18.5) | 1.15 (0.83–1.59) | |
Victim of spousal abuse | No | 431 (95.5) | 841 (96.4) | Ref |
Yes | 20 (4.5) | 31 (3.6) | 0.79 (0.42–1.48) | |
Estimated IQ (All participants) | ≤ 84 | 106 (23.4) | 88 (10) | Ref |
85–99 | 167 (37) | 301 (34.5) | 2.17 (1.47–3.22)*** | |
100–114 | 135 (29.9) | 337 (38.6) | 3.02 (2.01–4.53)*** | |
≥ 115 | 44 (9.7) | 147 (16.8) | 4.06 (2.34–7.03)*** | |
Estimated IQ (Native English only n = 968) | ≤ 84 | 42 (14.9) | 50 (7.2) | Ref |
85–99 | 98 (34.8) | 217 (31.6) | 1.86 (1.05–3.3)* | |
100–114 | 102 (36.3) | 284 (41.4) | 2.33 (1.36–4.01)** | |
≥ 115 | 39 (14.1) | 136 (19.8) | 2.9 (1.47–5.73)** | |
Parity | 0 | 239 (53) | 515 (59.1) | Ref |
1-Feb | 187 (41.5) | 324 (37.1) | 0.8 (0.63–1.02) | |
3+ | 25 (5.5) | 33 (3.8) | 0.62 (0.36–1.07) | |
Body Mass Index | Underweight | 11 (2.5) | 10 (1.1) | 0.43 (0.18–1.04) |
Normal weight | 174 (38.5) | 346 (39.6) | Ref | |
Overweight | 107 (23.8) | 278 (31.8) | 1.3 (0.97–1.74) | |
Obese | 159 (35.1) | 239 (27.4) | 0.76 (0.58–1.00) | |
Pregnancy planning | Planned | 373 (82.7) | 715 (82) | Ref |
Unplanned | 78 (17.3) | 157 (18) | 1.05 (0.77–1.42) | |
Infant factors | ||||
Baby sex | Male | 230 (51) | 461 (52.9) | Ref |
Female | 221 (49) | 411 (47.1) | 0.93 (0.74–1.17) | |
Gestational age | Not preterm (37+ weeks) | 418 (92.6) | 839 (96.2) | Ref |
Preterm (<=36 weeks) | 33 (7.4) | 33 (3.8) | 0.5 (0.3–0.81)** | |
Birthweight | Not small (>10th percentile) | 396 (87.8) | 786 (90.1) | Ref |
Small (<= 10th percentile) | 55 (12.2) | 86 (9.9) | 0.79 (0.55–1.13) | |
Head circumference | Not small | 426 (94.4) | 837 (96) | Ref |
Small (<3rd percentile) | 25 (5.6) | 35 (4) | 0.71 (0.41–1.23) | |
Apgar score (at 5mins) | > = 7 | 444 (98.4) | 854 (97.9) | Ref |
<7 | 7 (1.6) | 18 (2.1) | 1.31 (0.45–3.83) |
Characteristics associated with paternal drinking
PAE and infant GM development
Unadjusted b (95%CI) | Adjusted for maternala b (95%CI) | Adjusted for maternalb b (95%CI) | Adjusted for maternalc b (95%CI) | Adjusted for maternal + infantd b (95%CI) | |
---|---|---|---|---|---|
Trimester 1a (first 6 weeks) (n = 1324) | |||||
Abstinent | Ref | Ref | Ref | Ref | Ref |
Low (≤7 drinks per week, up to 2 per occasion) | −0.29 (−0.68–0.11) | −0.35 (−0.75–0.05) | −0.35 (−0.74–0.05) | −0.37 (−0.78–0.03) | −0.39 (−0.79–0.01) |
Moderate (≤7 drinks per week, > 2 to ≤4 per occasion) | − 0.49 (−1.24–0.27) | − 0.64 (−1.39–0.12) | − 0.63 (−1.39–0.12) | − 0.62 (−1.38–0.14) | − 0.66 (−1.42–0.1) |
Binge (≤7 drinks per week, > 4 per occasion) | − 0.23 (− 0.66–0.19) | −0.32 (− 0.75–0.12) | −0.31 (− 0.75–0.13) | −0.29 (− 0.74–0.15) | −0.3 (− 0.74–0.15) |
Heavy (> 7 drinks per week, weekly or more) | 0.02 (− 0.44–0.48) | − 0.04 (− 0.5–0.42) | − 0.02 (− 0.5–0.45) | −0.02 (− 0.5–0.46) | −0.06 (− 0.54–0.42) |
Trimester 1b* (second 6 weeks) (n = 1227) | |||||
Abstinent | Ref | Ref | Ref | Ref | Ref |
Low (≤7 drinks per week, up to 2 per occasion) | −0.23 (− 0.63–0.17) | −0.31 (− 0.71–0.09) | −0.3 (− 0.71–0.1) | −0.31 (− 0.72–0.1) | −0.32 (− 0.73–0.09) |
Trimester 2* (n = 1259) | |||||
Abstinent | Ref | Ref | Ref | Ref | Ref |
Low (≤7 drinks per week, up to 2 per occasion) | −0.02 (− 0.35–0.32) | 0.03 (− 0.32–0.37) | 0.03 (− 0.32–0.38) | 0.02 (− 0.33–0.37) | − 0.01 (− 0.36–0.34) |
Trimester 3* (n = 1270) | |||||
Abstinent | Ref | Ref | Ref | Ref | Ref |
Low (≤7 drinks per week, up to 2 per occasion) | −0.12 (− 0.46–0.21) | −0.03 (− 0.37–0.31) | −0.03 (− 0.38–0.31) | −0.04 (− 0.4–0.31) | −0.08 (− 0.43–0.28) |
Unadjusted M (95%CI) | Adjusted for maternala M (95%CI) | Adjusted for maternalb M (95%CI) | Adjusted for maternalc M (95%CI) | Adjusted for maternal + infantd M (95%CI) | |
---|---|---|---|---|---|
Trimester 1a (first 6 weeks) (n = 1324) | |||||
Abstinent | 9.31 (9.08–9.54) | 9.35 (9.12–9.59) | 9.35 (9.11–9.59) | 9.35 (9.11–9.59) | 9.36 (9.12–9.6) |
Low (≤7 drinks per week, up to 2 per occasion) | 9.02 (8.71–9.34) | 9 (8.69–9.32) | 9 (8.69–9.32) | 8.98 (8.66–9.29) | 8.98 (8.66–9.29) |
Moderate (≤7 drinks per week, > 2 to ≤4 per occasion) | 8.82 (8.11–9.54) | 8.72 (8.01–9.43) | 8.72 (8–9.43) | 8.73 (8.02–9.45) | 8.71 (7.99–9.43) |
Binge (≤7 drinks per week, > 4 per occasion) | 9.08 (8.72–9.44) | 9.04 (8.68–9.4) | 9.04 (8.68–9.4) | 9.06 (8.7–9.42) | 9.07 (8.7–9.43) |
Heavy (> 7 drinks per week, weekly or more) | 9.33 (8.94–9.72) | 9.31 (8.92–9.7) | 9.33 (8.93–9.72) | 9.33 (8.93–9.73) | 9.31 (8.91–9.71) |
Trimester 1b* (second 6 weeks) (n = 1227) | |||||
Abstinent | 9.23 (9.06–9.4) | 9.24 (9.07–9.41) | 9.24 (9.07–9.41) | 9.24 (9.07–9.41) | 9.25 (9.08–9.42) |
Low (≤7 drinks per week, up to 2 per occasion) | 9 (8.64–9.35) | 8.93 (8.58–9.29) | 8.94 (8.58–9.3) | 8.93 (8.57–9.3) | 8.92 (8.56–9.29) |
Trimester 2* (n = 1259) | |||||
Abstinent | 9.16 (8.99–9.33) | 9.15 (8.98–9.32) | 9.15 (8.97–9.32) | 9.15 (8.98–9.33) | 9.16 (8.98–9.33) |
Low (≤7 drinks per week, up to 2 per occasion) | 9.15 (8.86–9.43) | 9.18 (8.89–9.47) | 9.18 (8.89–9.47) | 9.17 (8.87–9.46) | 9.15 (8.86–9.44) |
Trimester 3* (n = 1270) | |||||
Abstinent | 9.22 (9.04–9.39) | 9.19 (9.02–9.37) | 9.19 (9.02–9.37) | 9.2 (9.02–9.37) | 9.21 (9.03–9.38) |
Low (≤7 drinks per week, up to 2 per occasion) | 9.09 (8.81–9.38) | 9.16 (8.87–9.45) | 9.16 (8.87–9.45) | 9.15 (8.86–9.45) | 9.13 (8.83–9.43) |