|
| Study reference | Year of birth | Country | Asthma Outcome | Age at follow up | Number in cohort | Positive or negative | Magnitude of effect* |
|
| [21] | 1928–1952 | Sweden | Doctor diagnosed asthma, asthma admission or death | 36–70 years | 21,588 twins | Negative | OR for 2 kg 1.58 [1.06, 2.38] compared to 2.5 kg |
| [27] | 1947–1973 | Nordic-Baltic countries | Wheeze, wheeze with shortness of breath | 20–47 years | 1683 | No association | Wheeze reduced by 2% [±19%] for each 500 g wt gainBirth weight 2500 versus 4000 g linked with 8% increase in FEV1 |
| [32] | 1966 | Finland | Doctor diagnosed asthma ever and symptoms in last 12 months | 31 years | 4719 | No association | Using ponderal index tertiles and middle as reference, risk for asthma in lowest 1.14 [0.78, 1.65] and for highest 1.22 [0.85, 1.75]. Ponderal index had significant U-shaped relationship with skin prick positivity |
| [15] | 1970–1989 | UK | Hospital admission for asthma | 2–10 years | 248612 recruited 4017 admitted | Negative | Risk increased 20% [10–30] comparing 1–3 kg versus 3–4 kg |
| [30] | 1975–1979 | Finland | Life time prevalence doctor-diagnosed asthma | 16 years | 3065 twin pairs | No association | OR 0.61 [0.30, 1.24] for 2.5–3 kg versus <2 kg. OR highest versus lowest quartile for ponderal index (wt/length3) 1.82 [1.18, 2.79] |
| [26] | 1975–1988 | UK | Asthma diagnosis | 13–14 years | 10,809 | No association for birth weight | Highest versus lowest quintile head circumference increased hay fever (1.23 [1.03, 1.47]). Highest quintile birth wt increased hayfever (1.17 [0.99, 1.39]). Highest versus lowest birth weight 0.92 [0.62, 1.35] |
| [25] | 1977–1980 | Australia | Asthma | Mean 14 years | 180 preterm and 42 term deliveries | No association | Asthma prevalence 21% in controls, 21% in 1–1.5 kg birth wt and 15% in 0.5–1 kg birth wt |
| [35] | 1984–1987 | Denmark | Hospital admission for “definite” or “any” asthma | 12 years | 10440 | Positive | Definite asthma increased 1.62 [1.02, 2.59] for above compared with below average birth weight. More convincing relationship between increasing ponderal index and any and definite asthma admission |
| [34] | 1985–1988 | Canada | Emergency visits for asthma | 10 years | 83,595 children | Positive above 4.5 kg | Above 4.5 kg increased risk (1.16 [1.04, 1.29]) compared to normal weight. Beyond 4.5 kg 10% increase risk [2, 19]. |
| [33] | 1986 | Finland | Doctor diagnosed asthma | 16 | 9479 | Positive at very highest weight | Highest birth wt (>4.51 kg) had greatest atopic asthma risk 2.4 [1.33, 4.32] compared to 2.5–3.34 kg |
| [16] | 1987 | Finland | Hospitalisation or free entitlement to asthma medication | 7 years | 60254 | Negative | Birth wt < 2.5 kg OR for asthma 1.83 [1.50, 2.24] independent of maternal smoking |
| [14] | 1988 | USA | Physician diagnosed asthma by age 3 years | 0–4 years | 8071 | Negative | <1.5 kg OR 2.9 [2.3, 3.6], 1.5–2.5 kg OR 1.4 [1.1, 1.8] compared to ≥2.5 kg |
| [23] | 1988–1990 | Netherlands | Parent reported asthma | Mean 6 years | 1961 | No association for birth weight | Relationship between asthma and gestational age (risk for >36 weeks 2.0 [1.0, 4.0] compared to 40 weeks) and asthma and head circumference : birth weight ratio (risk for above median 1.8 [1.1, 3.2] compared with below median). |
| [20] | 1992–1998 | Sweden | Ever had asthma | 9–12 years | 446 twins | Negative | OR 1.57 [1.38, 1.79] for each kg decrease |
| [28] | 1994–1996 | Sweden | Wheeze | 4 years | 2869 | No association for birth weight | Birth length ≥ 90th centile OR any wheeze 0.4 [0.21, 0.77] |
| [29] | 1994–1996 | USA | Physician diagnosed plus wheeze in the last year | 6 years | 454 at risk for asthma | No association | Birth weight < 2.5 kg OR asthma 1.05 [0.40, 2.73]. Gestation < 38.5 weeks assoc with increased asthma (OR 4.7 [2.1, 10.5]) |
| [17] | 1994–2000 | Denmark | History of asthma | 3-9 years | 8280 twin pairs | Negative | Asthma assoc with 122 g lower birth weight [85, 160]. Risk increased by 4% per 100 g wt reduction |
| [31] | 1995–2001 | Canada | Hospital admission or >1 physician visits with asthma over 2 years | 6 | 687,194 | No association | Extremely heavy (>6.5 kg) OR 1.21 [0.67, 2.19] |
| [22] | Approx 1995–2001 | USA | ? | 1–5 years | 2410 | Negative | Linear 20% increase risk [2, 35] for each kg reduction in birth weight. Breast feeding apparently protective of influence of low birth weight |
| [24] | 1996-1997 | Netherlands | Doctor diagnosed | Mean 7 years | 3628 | No association | Relationship between birth weight and wheeze (risk increased by 17% [1, 35] for each kg reduction in birth weight |
| [18] | 1996–2004 | Finland | Asthma diagnosis and prescribed inhaled steroids or montelukast | Three years | 20,623 case-control pairs | Negative | Birth weight < 2.5 kg OR 1.40 [1.20, 1.60] |
| [19] | 1998–2000 | USA | Asthma diagnosis | 3 | 1803 | Negative | Birth weight < 2.5 kg OR 2.36 [CI not given] |
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