Table 2. Mean of characteristics and distribution of interventions for multiparous women delivering vaginally grouped by infant’s birthweight according to smoking status group between 1997 and 2007 in Finland (n = 296,963) (Chi-Square, Kruskal-Wallis tests).
| Characteristic/intervention | <3,000 g | 3,000–3,499 g | 3,500–3,999 g | 4,000–4,499 g | 4,500–4,999 g | ≥5,000 g | Pooled |
| % or mean | % or mean | % or mean | % or mean | % or mean | % or mean | % or mean | |
| OASIS, n (%) | |||||||
| Smoking | 4 (0.1) | 7 (0.2) | 20 (0.2) | 12 (0.3) | 3 (0.5) | 0 | 46 (0.1)** |
| Given up smoking | 0 | 1 (0.1) | 0 | 1 (0.1) | 0 | 0 | 2 (0.0) |
| Non-smoking | 9 (0.0) | 56 (0.1) | 192 (0.2) | 155 (0.3) | 48 (0.5) | 8 (0.9) | 468 (0.2) |
| Mean maternal age | |||||||
| Smoking | 29.6*** | 29.1*** | 29.2*** | 29.5*** | 29.8*** | 31.4 | 29.3*** |
| Given up smoking | 29.7 | 29.3 | 29.5 | 29.5 | 29.0 | 31.7 | 29.4 |
| Non-smoking | 31.1 | 30.9 | 31.0 | 31.1 | 31.4 | 31.5 | 31.0 |
| Mean maternal weight (kg) | |||||||
| Smoking | 62.7 | 66.0*** | 69.3*** | 74.0*** | 78.3*** | 82.7 | 67.6*** |
| Given up smoking | 63.6 | 65.4 | 68.3 | 71.0 | 75.0 | 77.2 | 67.7 |
| Non-smoking | 62.7 | 64.4 | 67.0 | 70.4 | 73.3 | 78.5 | 66.8 |
| Mean birthweight (g) | |||||||
| Smoking | 2642.4*** | 3264.5*** | 3720.3*** | 4181.5*** | 4651.7 | 5201.0 | 3443.2*** |
| Given up smoking | 2683.1 | 3285.0 | 3740.5 | 4195.7 | 4661.4 | 5120.4 | 3630.2 |
| Non-smoking | 2659.8 | 3287.4 | 3737.9 | 4193.0 | 4659.4 | 5175.2 | 3665.9 |
| Mean birth height (cm) | |||||||
| Smoking | 46.6*** | 49.2*** | 50.7*** | 52.1*** | 53.4** | 54.6 | 49.7*** |
| Given up smoking | 46.9 | 49.4 | 50.8 | 52.1 | 53.4 | 54.7 | 50.4 |
| Non-smoking | 46.9 | 49.5 | 50.9 | 52.3 | 53.6 | 54.9 | 50.6 |
| Mean head circumference (cm) | |||||||
| Smoking | 33.0 | 34.4** | 35.3** | 36.2 | 37.0 | 37.6 | 34.7*** |
| Given up smoking | 33.2 | 34.3 | 35.3 | 36.1 | 36.9 | 37.6 | 35.0 |
| Non-smoking | 33.0 | 34.4 | 35.3 | 36.2 | 36.9 | 37.6 | 35.1 |
| Vacuum | |||||||
| Smoking | 1.5 | 1.7 | 2.3 | 3.0 | 3.6 | 2.0 | 2.0 |
| Given up smoking | 0.7 | 2.3 | 2.4 | 3.3 | 1.9 | 0 | 2.3 |
| Non-smoking | 1.6 | 1.7 | 2.1 | 2.7 | 3.4 | 4.4 | 2.2 |
| Mean length of active 2nd stage (min.) | |||||||
| Smoking | 9.4 | 11.0 | 13.2 | 14.2 | 18.6 | 36.7 | 12.0*** |
| Given up smoking | 9.0 | 11.9 | 14.2 | 16.2 | 20.1 | 25.2 | 13.6 |
| Non-smoking | 9.7 | 11.4 | 13.6 | 15.4 | 18.1 | 23.5 | 13.2 |
*
p value <0.05,
**
p<0.01,
***
p<0.001.
Information on maternal height and weight, head circumference and length of the active second stage of birth have been recorded in the MBR since 2004 (n = 80,504).