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Correction: http://dx.doi.org/10.1136/bmjopen-2016-012894corr1 Objective: To assess the association between perinatal losses and mother’s long-term mortality and modification by surviving children and attained education. Design: A population-based cohort study. Setting: Norwegian national registries. Participants: We followed 652 320 mothers with a first delivery from 1967 and completed reproduction before 2003, until 2010 or death. We excluded mothers with plural pregnancies, without information on education (0.3%) and women born outside Norway. Main outcome measures: Main outcome measures were age-specific (40–69 years) cardiovascular and non-cardiovascular mortality. We calculated mortality in mothers with perinatal losses, compared with mothers without, and in mothers with one loss by number of surviving children in strata of mothers’ attained education (

OBJECTIVE—To assess whether alcohol and caffeine are independent risk factors for sudden infant death syndrome (SIDS). MATERIALS AND METHODS—Analyses based on data from the Nordic epidemiological SIDS study, a case control study in which all parents of SIDS victims in the Nordic countries from 1 September 1992 to 31 August 1995were invited to participate with parents of four controls, matched for sex and age at death. Odds ratios (ORs) were calculated by conditional logistic regression analysis. RESULTS—The crude ORs for caffeine consumption > 800 mg/24 hours both during and after pregnancy were significantly raised: 3.9 (95% confidence interval (CI), 1.9 to 8.1) and 3.1 (95% CI, 1.5 to 6.3), respectively. However, after adjustment for maternal smoking in 1st trimester, maternal age, education and parity, no significant effect of caffeine during or after pregnancy remained. For maternal or paternal alcohol use, no significant risk increase was found after adjusting for social variables, except for heavy postnatal intake of alcohol by the mother, where the risk was significantly increased. CONCLUSIONS—Caffeine during or after pregnancy was not found to be an independent risk factor for SIDS after adjustment for maternal age, education, parity, and smoking during pregnancy. Heavy postnatal but not prenatal intake of alcohol by the mother increased the risk.

Aim—To establish whether smoking is an independent risk factor for sudden infant death syndrome (SIDS), if the eVect is mainly due to prenatal or postnatal smoking, and the eVect of smoking cessation. Methods—The analyses were based on data from the Nordic epidemiological SIDS study, a case-control study with 244 cases and 869 controls. Odds ratios were computed by conditional logistic regression analysis. Results—Smoking emerged as an independent risk factor for SIDS, and the eVect was mainly mediated through maternal smoking in pregnancy (crude odds ratio 4.0 (95% confidence interval 2.9 to 5.6)). Maternal smoking showed a marked dose‐response relation. There was no eVect of paternal smoking if the mother did not smoke. Stopping or even reducing smoking was beneficial. SIDS cases exposed to tobacco smoke were breast fed for a shorter time than non-exposed cases, and feeding diYculties were also more common. Conclusions—Smoking is an independent risk factor for SIDS and is mainly mediated through maternal smoking during pregnancy. Stopping smoking or smoking less may be beneficial in reducing the risk of SIDS. (Arch Dis Child 1998;78:329‐334)

AIMS: To consider the prognostic role of oestrogen receptor and progesterone receptor status in relation to the age at surgery, length of follow up and lymph node status. METHODS: The study population comprised 977 patients with histologically confirmed breast carcinoma, with a median follow up of nine years. The actuarial life table method was used to test for survival differences. The Cox proportional hazard model was used to test for interaction effects between each hormone receptor and age, lymph node status and length of follow up. As the analysis involved multiple subgroups, significance was set at the 1% level (p < 0.01). RESULTS: When the patients were subdivided into groups according to lymph node status and age, progesterone and oestrogen receptor status predicted prognosis in middle aged (46-60 years) patients with lymph node positive breast cancer. Their prognostic effect in this subgroup, however, was restricted to the first five years after surgery. Progesterone receptor status was the strongest predictor of outcome. CONCLUSION: The prognostic power of oestrogen and progesterone receptor status varies depending on age, lymph node status and length of follow up after surgery.

OBJECTIVE--To investigate, in a population based national study, the association between sleeping position of infants and the occurrence of sudden infant death syndrome (SIDS). DESIGN--A retrospective survey and registry based ecological study. A questionnaire based surveillance of sleeping position was obtained in a random sample (n = 34,799) and surveillance of SIDS was based on all infants born in Norway 1967-91, surviving the perinatal period. Variables studied from the questionnaire were usual sleeping position (placed), breast feeding at 3 months, and maternal smoking in pregnancy, and from the Medical Birth Registry maternal age, birth order, and birth weight. RESULTS--Proportion of infants sleeping prone increased from 1970 (7.4%) to 1989 (49.1%) and dropped in 1990 (26.8%) and 1991 (28.3%). Occurrence of SIDS increased from 1970 (1.1/1000) to 1989 (2.0) before dropping in 1990 and 1991 (1.1). IMPLICATION AND RELEVANCE OF RESULTS--A cause effect relationship between prone sleeping and SIDS as suggested in previous studies is supported by the present; and so far only, national study of infants' sleeping position.

Aims: To assess the effects of breast feeding habits on sudden infant death syndrome (SIDS). Methods: The analyses are based on data from the Nordic Epidemiological SIDS Study, a case–control study in which parents of SIDS victims in the Scandinavian countries between 1 September 1992 and 31 August 1995 were invited to participate, each with parents of four matched controls. The odds ratios presented were computed by conditional logistic regression analysis. Results: After adjustment for smoking during pregnancy, paternal employment, sleeping position, and age of the infant, the adjusted odds ratio (95% CI) was 5.1 (2.3 to 11.2) if the infant was exclusively breast fed for less than four weeks, 3.7 (1.6 to 8.4) for 4–7 weeks, 1.6 (0.7 to 3.6) for 8–11 weeks, and 2.8 (1.2 to 6.8) for 12–15 weeks, with exclusive breast feeding over 16 weeks as the reference. Mixed feeding in the first week post partum did not increase the risk. Conclusions: The study is supportive of a weak relation between breast feeding and SIDS reduction.

Objective To assess the association of pre-eclampsia with later cardiovascular death in mothers according to their lifetime number of pregnancies, and particularly after only one child. Design Prospective, population based cohort study. Setting Medical Birth Registry of Norway. Participants We followed 836 147 Norwegian women with a first singleton birth between 1967 and 2002 for cardiovascular mortality through linkage to the national Cause of Death Registry. About 23 000 women died by 2009, of whom 3891 died from cardiovascular causes. Associations between pre-eclampsia and cardiovascular death were assessed by hazard ratios, estimated by Cox regression analyses. Hazard ratios were adjusted for maternal education (three categories), maternal age at first birth, and year of first birth Results The rate of cardiovascular mortality among women with preterm pre-eclampsia was 9.2% after having only one child, falling to 1.1% for those with two or more children. With term pre-eclampsia, the rates were 2.8% and 1.1%, respectively. Women with pre-eclampsia in their first pregnancy had higher rates of cardiovascular death than those who did not have the condition at first birth (adjusted hazard ratio 1.6 (95% confidence interval 1.4 to 2.0) after term pre-eclampsia; 3.7 (2.7 to 4.8) after preterm pre-eclampsia). Among women with only one lifetime pregnancy, the increase in risk of cardiovascular death was higher than for those with two or more children (3.4 (2.6 to 4.6) after term pre-eclampsia; 9.4 (6.5 to 13.7) after preterm pre-eclampsia). The risk of cardiovascular death was only moderately elevated among women with pre-eclamptic first pregnancies who went on to have additional children (1.5 (1.2 to 2.0) after term pre-eclampsia; 2.4 (1.5 to 3.9) after preterm pre-eclampsia). There was little evidence of additional risk after recurrent pre-eclampsia. All cause mortality for women with two or more lifetime births, who had pre-eclampsia in first pregnancy, was not elevated, even with preterm pre-eclampsia in first pregnancy (1.1 (0.87 to 1.14)). Conclusions Cardiovascular death in women with pre-eclampsia in their first pregnancy is concentrated mainly in women with no additional births. This association might be due to health problems that discourage or prevent further pregnancies rather than to pre-eclampsia itself. As a screening criterion for cardiovascular disease risk, pre-eclampsia is a strong predictor primarily among women with only one child—particularly with preterm pre-eclampsia.