Cigarette smoking in pregnancy: its influence on birth weight and perinatal mortality

In a British population cigarette smoking during pregnancy increased the late fetal plus neonatal mortality rate by 28% and reduced birth weight by 170 g, and these differences persist even after allowing for a number of "mediating" maternal and social variables. A change in smoking habit by the end of the fourth month of pregnancy places a mother in the risk category appropriate to her changed habit. This evidence should have important implications for health education aimed at getting pregnant mothers to give up smoking.

Smoking in pregnancy and subsequent child development

A national sample of several thousand children has been followed longitudinally from birth. At the ages of 7 and 11 years physical and mental retardation due to smoking in pregnancy has been found, and this deficit increases with the number of cigarettes smoked after the fourth month of pregnancy. Children of mothers who smoked 10 or more cigarettes a day are on average 1.0 cm shorter and between three and five months retarded on reading, mathematics, and general ability compared with the offspring of non-smokers, after allowing for associated social and biological factors.

Febrile convulsions in a national cohort followed up from birth. I--Prevalence and recurrence in the first five years of life

Of 13 135 children followed up from birth to the age of 5 years, 303 (2.3%) had febrile convulsions. Prior neurological abnormality had been noted in 13. Of the 290 remaining children, 57 (20%) presented with a complex convulsion, and 103 children (35%) went on to have further febrile convulsions. The risk of further febrile convulsions varied with the age at first convulsion and the presence of a history of convulsive disorders in relatives. There were no significant differences between the sexes.

Epilepsy in childhood: findings from the National Child Development Study

By the age of 11 years 1043 children (6.7%) in an unselected national sample had a history of seizures or other episodes of loss of consciousness; 322 (20.8/1000) had a history of febrile convulsions without other epileptic problems. A clear-cut diagnosis of non-febrile epilepsy was established in 64 children (4.1/1000) by the age of 11 on the basis of confirmatory information supplied by family doctors and paediatricians. A further 39 (2.6/1000) were reported as having epilepsy but did not fulfil the study criteria. The progress of 59 of the 64 children with estabished epilepsy was reviewed again when they were aged 16. Of the 37 educated in normal schools eight (22%) had one or more seizures in their 16th year compared with 13 out of 22 (59%) who received special education. A possible cause for epilepsy was found in 17 of the 64 (27%) children, but for the majority there was no obvious reason.

Febrile convulsions in a national cohort followed up from birth. II--Medical history and intellectual ability at 5 years of age

Three hundred and three children with febrile convulsions were identified in a national birth cohort of 13 135 children followed up from birth to the age of 5 years. Breech delivery (p less than 0.05) was the only significantly associated prenatal or perinatal factor. There were no associations with socioeconomic factors. Excluding the 13 known to be neurologically abnormal before their first febrile convulsion, children who had had a febrile convulsion did not differ at age 5 from their peers who had not had febrile convulsions in their behaviour, height, head circumference, or performance in simple intellectual tests.

Advantages of aluminium hydroxide adsorbed combined diphtheria, tetanus, and pertussis vaccines for the immunization of infants

Three combined triple antigen vaccines were used to inoculate infants receiving primary immunization at 3 to 6 months of age. Laboratory potency and toxicity tests and clinical evaluation again showed that the mouse weight gain test is able to predict which vaccines will give reactions in children. The addition of aluminium hydroxide to the vaccine both increased potency and reduced the tendency to cause reactions. Assays on sera showed that almost all children produced agglutinins to Bordetella pertussis types 1, 2, and 3 when the vaccine contained aluminium hydroxide.

Teenage mothering, admission to hospital, and accidents during the first 5 years

One thousand and thirty-one singleton children of teenage mothers were compared with 10 950 singleton children of older mothers in a national longitudinal cohort study. Children born to teenage mothers and living with them during the first 5 years were more liable to hospital admissions, especially after accidents and for gastroenteritis, than were children born to and living with older mothers. Frequent accidents, poisoning, burns, and superficial injuries or lacerations were more often reported by teenage mothers. The association of teenage mothering with greater likelihood that children would have accidents or be admitted to hospital remained highly significant even after controlling for social and biological confounding influences. Although in part a marker for adverse socioeconomic circumstances, low maternal age appears to be a health hazard for children.

Parental smoking and post-infancy wheezing in children: a prospective cohort study

The contribution of parental smoking to wheezing in children was studied in a subset of all British births between April 5 and 11, 1970 (N = 9,670). Children of smoking mothers had an 18.0 per cent cumulative incidence of post-infancy wheezing through 10 years of age, compared with 16.2 per cent among children of nonsmoking mothers (risk ratio 1.11, 95% CI: 1.02, 1.21). This difference was confined to wheezing attributed to wheezy bronchitis, of which children of smokers had 7.4 per cent, and those of nonsmokers had 5.2 per cent (risk ratio 1.44, 95% CI: 1.24, 1.68). The incidence of wheezy bronchitis increased as mothers smoked more cigarettes. After multiple logistic regression analysis was used to control for paternal smoking, social status, sex, family allergy, crowding, breast-feeding, gas cooking and heating, and bedroom dampness, the association of maternal smoking with childhood wheezy bronchitis persisted. Some of this effect was explained by maternal respiratory symptoms and maternal depression, but not by neonatal problems, the child's allergic symptoms, or paternal respiratory symptoms. There was a 14 per cent increase in childhood wheezy bronchitis when mothers smoked over four cigarettes per day, and a 49 per cent increase when mothers smoked over 14 cigarettes daily.

Plus ça change: predictors of birthweight in two national studies

The 16 989 singleton births in one week of March, 1958, studied by the British Perinatal Mortality Survey, were subjected to an analysis of covariance, which showed that major factors associated with birthweight of the infant were: maternal height, history of smoking in pregnancy, parity and history of pre-eclampsia during the pregnancy. The same analysis was repeated on the data collected on 16792 singletons born 12 years later in one week of April, 1970 and studied by the British Births Survey. In spite of major changes in obstetric practice and in the maternal population, the same factors were shown to be highly significant and the magnitude of the associations had changed little.

Intended place of delivery and perinatal outcome

Data from the "1958 Perinatal Mortality Survey" have been analysed to assess differences in stillbirth and neonatal death rates according to the arrangements made for delivery. Only women aged 20-34 delivering at term, with no pregnancy abnormalities, were selected from three groups of women (normotensive primiparae, hypertensive primiparae, and normotensive women of parity 1, 2, or 3). Despite the fact that within each group the women booked for NHS consultant units were heavily weighted with adverse factors, the death rate of their infants was no more than 70% of that found among the women booked for either domiciliary, general practitioner unit, or private consultant delivery. Care and delivery in a NHS consultant unit carries least risk of death for the infant.

A trial of health education aimed to reduce cigarette smoking among pregnant women

Three hundred and forty-six women who reported smoking one or more cigarettes per day prior to the 20th week of gestation were recruited into a trial of health educational counselling to stop or reduce cigarette smoking. Counselling was begun at the first prenatal visit and then continued subsequently in the home. Among the 319 women included in analysis, at first follow-up visit those who received counselling smoked 1.7 fewer cigarettes a day than control women (P less than 0.05) and 10.4% had stopped smoking, compared to 5.4% in the control group (NS). Similar but not significant differences were noted at the end of pregnancy. Study effects were limited to the 284 women smoking five or more cigarettes a day at booking. This report refers primarily to them. At first follow-up visit the proportion of such women in the counselled group who ceased smoking (9.3%) was significantly greater than in the control group (2.6%; P less than 0.05). The magnitude of this difference persisted through late pregnancy (11.8% vs. 4.3%; NS) and delivery (10.6% vs. 4.7%; NS). The differences between counselled women and controls in numbers of cigarettes reported smoked at first and last prenatal follow-up visits (2.4 and 2.1) and at delivery (2.0) were all statistically significant. While there was no effect of counselling on either serum thiocyanate or end expiratory carbon monoxide, the counselled group gained slightly more weight than controls during the study (0.47 vs. 0.44 kg per week among controls; NS), and their infants had modestly higher birthweight (44 g; NS).

Delayed onset of regular respiration and subsequent development

A comprehensive survey carried out at birth, data on mortality and a 5 year follow-up covering medical, educational and sociological aspects of child development were available for singleton births born in one week of April 1970. The survey at 5 years of age included 12363 children, 79.6% of the surviving cohort. An assessment has been made of the extent to which delay in the onset of regular respiration at birth is associated with the subsequent development of the child. Using the results of our previous investigations, the relationships between this delay and other factors known at the time of birth have been taken into account. The distributions of a large number of development variables were not significantly different for groups of children determined by respiratory delay at birth, but there was an association with mortality and cerebral palsy. In addition, there was an unexpected relationship between delayed onset of respiration and subsequent bronchitis. This association remained significant after controlling for possible confounding effects using linear modelling techniques.