Is smoking an extra hazard in pregnant MS women? Findings from a population‐based registry in Norway

Multiple sclerosis (MS) in women leads to increased risk of operative delivery and reduced birth weight, which are presumably related to the neurological dysfunction in this patient group. Lifestyle factors may also contribute, and we therefore investigated smoking habits and relevant social factors in pregnant MS women. In total, 372 128 births were registered in the compulsory Medical Birth Registry of Norway from December 1, 1998 to October 6, 2005, and of them 250 by MS mothers. The MS births were compared with all the non-MS births. Smoking during pregnancy was not increased in the MS group compared with the non-MS references. From 1998 to 2005 the MS group had a larger reduction in smoking rate during pregnancy than the reference group. The differences in pregnancy and birth outcome between smokers and non-smokers were similar in the MS and the reference group. Those in the smoking MS group had no increase in birth complications, operative interventions or negative birth outcome compared with those in the smoking reference group. Smoking during pregnancy did not explain the birth weight reduction found for newborns of MS mothers.     

Birth defects in Norway by levels of external and food-based exposure to radiation from Chernobyl.

In Norway, external doses of radiation resulting from fallout from the Chernobyl nuclear accident were estimated from detailed measurements, including soil deposition patterns. Internal doses were estimated from measurements of radioactive cesium in meat and milk supplies. The doses were calculated as average monthly doses for each of 454 municipalities during 36 consecutive months after the accident in spring 1986. Prospectively collected data on all newborns listed in the Medical Birth Registry of Norway who were conceived in the period May 1983-April 1989 were used to assess possible dose-response relations between estimated external and food-based exposures and congenital malformations and some other conditions. A positive association was observed between total radiation dose (external plus food-based) and hydrocephaly, while a negative association was observed for Down's syndrome. However, an important conclusion of the study was that no associations were found for conditions previously reported to be associated with radiation, i.e., small head circumference, congenital cataracts, anencephaly, spina bifida, and low birth weight. Potential sources of bias, including exposure misclassification and incomplete ascertainment of cases, are discussed.     

Genetic variants in IRF6 and the risk of facial clefts: single-marker and haplotype-based analyses in a population-based case-control study of facial clefts in Norway

Mutations in the gene encoding interferon regulatory factor 6 (IRF6) underlie a common form of syndromic clefting known as Van der Woude syndrome. Lip pits and missing teeth are the only additional features distinguishing the syndrome from isolated clefts. Van der Woude syndrome, therefore, provides an excellent model for studying the isolated forms of clefting. From a population-based case-control study of facial clefts in Norway (1996-2001), we selected 377 cleft lip with or without cleft palate (CL/P), 196 cleft palate only (CPO), and 763 control infant-parent triads for analysis. We genotyped six single nucleotide polymorphisms within the IRF6 locus and estimated the relative risks (RR) conferred on the child by alleles and haplotypes of the child and of the mother. On the whole, there were strong statistical associations with CL/P but not CPO in our data. In single-marker analyses, mothers with a double-dose of the 'a'-allele at rs4844880 had an increased risk of having a child with CL/P (RR=1.85, 95% confidence interval: 1.04-3.25; P=0.036). An RR of 0.38 (95% confidence interval: 0.16-0.92; P=0.031) was obtained when the child carried a single-dose of the 'a'-allele at rs2235371 (the p.V274I polymorphism). The P-value for the overall test was <0.001. In haplotype analyses, several of the fetal and maternal haplotype relative risks were statistically significant individually but were not strong enough to show up on the overall test (P=0.113). Taken together, these findings further support a role for IRF6 variants in clefting of the lip and provide specific risk estimates in a Norwegian population.     

Mothers' and fathers' birth characteristics and perinatal mortality in their offspring: a population‐based cohort study

Nordtveit TI, Melve KK, Skjaerven R. Mothers' and fathers' birth characteristics and perinatal mortality in their offspring: a population‐based cohort study. Paediatric and Perinatal Epidemiology 2010; 24: 282–292. There is increasing interest in the associations between parental birthweight and gestational age with their perinatal outcomes. We investigated perinatal mortality risk in offspring in relation to maternal and paternal gestational age and birthweight. We used population‐based generational data from the Medical Birth Registry of Norway, 1967–2006. Singletons in both generations were included, forming 520 794 mother–offspring and 376 924 father–offspring units. Perinatal mortality in offspring was not significantly associated with paternal gestational age or birthweight, whereas it was inversely associated with maternal gestational age. A threefold increased risk in perinatal mortality was found among offspring of mothers born at 28–30 weeks of gestation relative to offspring of mothers born at term (37–43 weeks) (relative risk: 2.9, 95% CI 1.9, 4.6). There was also an overall association between maternal birthweight and offspring perinatal mortality. Relative risk for mothers whose birthweight was <2000 g was 1.5 (95% CI 1.1, 1.9), relative to mothers whose birthweight was 3500–3999 g. However, confined to mothers born at ≥34 weeks of gestation, the birthweight association was not significant. Weight‐specific perinatal mortality in offspring was dependent on the birthweight of the mother and the father, that is, offspring who were small relative to their mother's or father's birthweight had increased perinatal mortality. In conclusion, a mother's gestational age, and not her birthweight, was significantly associated with perinatal mortality in the offspring, while there was no such association for the father.     

Parenthood probability and pregnancy outcome in patients with a cancer diagnosis during adolescence and young adulthood

BACKGROUND: To compare first-time parenthood probability and pregnancy outcome between cancer patients and the general population. METHODS: Data from a hospital registry on cancer patients aged 15-35 years at diagnosis, including date/type of diagnosis, treatment and date of death, were merged with data from the Cancer Registry and the Medical Birth Registry, providing date of childbirth, IVF, pregnancy outcomes and demographics. RESULTS: The first-time parenthood probability at the age of 35 years was 63% in male patients (n = 463) and 64% in the male general population (n = 367 068). Figures in female patients were 66% (n = 284) compared with 79% in the female general population (n = 349 576) (P = 0.007). A total of 487 male and 251 female cancer patients were childless pre-diagnosis, and 130 male and 104 female cancer patients had one child before diagnosis and at least one birth post-diagnosis. Congenital anomalies were more frequent in first-borns to previously childless male patients [adjusted odds ratio (OR(adj)): 1.5; 95% confidence interval (CI): 1.1-2.3]. The risk of low birth weight and preterm delivery after cancer was increased in infants born to female patients, as was perinatal mortality (OR(adj) 2.3; 95% CI: 1.1-5.0) among post-diagnosis first births. CONCLUSIONS: The first-time parenthood probability in 35-year old cancer patients is approximately 60%, which in female patients is significantly reduced compared with the general population. Post-diagnosis pregnancies to female patients are high-risk pregnancies.     

The relationship between maternal birthweight and gestational age in twins and singletons and those of their offspring in Norway

In order to elucidate whether maternal plurality affects offspring intrauterine growth, the relationship between birthweight and gestational age of twins and singletons and those of their first singleton liveborn children in Norway was studied using data from the Medical Birth Registry. The population-based sample consisted of 49 698 mother–offspring pairs (48 842 with singleton and 856 with twin-mothers). In bivariate analyses, no significant differences in mean birthweight and gestational age of offspring of twin and singleton mothers were found, although the mean birthweight and gestational age of the twin-mothers themselves were significantly lower than those of singletons (819 g and 14 days respectively). In multiple regression analysis, the expected birthweight of offspring was 230.3 g (95% CI: 193.2–267.4 g) higher when the mother was a twin than when the mother was a singleton, when controlling for non-standardised maternal birthweight. When adjusting for relative maternal birthweight ( z -score), the association between maternal plurality and offspring birthweight was not statistically significant. The results suggest that being born as a twin has no substantial consequences on offspring growth in utero and show that mean differences in birthweight between twins and singletons should be standardised when both groups are included in multivariate studies.     

Prognosis in node negative breast cancer patients: the importance of tumour diameter and mean nuclear area

In node negative breast cancer patients, tumour size and mean nuclear area (MNA) as single variables have significant impact on prognosis. Combination of the two variables gives additional information on survival, and makes it possible to predict the outcome of the disease correctly in 70% of the patients both early (82 months) and late (154 months). MNA contributes relatively more to prediction of late prognosis than tumour diameter and vice versa for early prognosis. Thus a long follow-up is needed for node negative patients, and more so for patients with favourable prognostic criteria.