Leisure-time physical activity before pregnancy and risk of hyperemesis gravidarum: a population-based cohort study.

INTRODUCTION: Women who experience severe nausea and vomiting in early pregnancy are less likely to participate in leisure-time physical activity (LTPA) during pregnancy. Whether LTPA before pregnancy is associated with hyperemesis gravidarum (HG) has not yet been studied. The aim of the study was to estimate associations between prepregnancy LTPA and HG in pregnancy. METHODS: We present data from 37,442 primiparous women with singleton pregnancies enrolled in The Norwegian Mother and Child Cohort Study. Prepregnancy LTPA was self-reported by questionnaire in pregnancy week 17. HG was reported in week 30 and defined as prolonged nausea and vomiting in pregnancy requiring hospitalisation before the 25th gestational week. We estimated the crude and adjusted associations between LTPA and HG using multiple logistic regression. We assessed effect modification by prepregnancy BMI or smoking by stratified analysis and interaction terms. RESULTS: A total of 398 (1.1%) women developed HG. Before pregnancy 56.7% conducted LTPA at least 3 times weekly, while 18.4% of women conducted LTPA less than once a week. Compared to women reporting LTPA 3 to 5 times weekly, women reporting no LTPA before pregnancy had an increased odds of HG (adjusted odds ratio (aOR) 1.69; 95% confidence interval (CI), 1.20 to 2.37). LTPA-HG associations differed by prepregnancy BMI but not by prepregnancy smoking. DISCUSSION: Lack of LTPA before pregnancy was associated with an increased odds of HG. Due to few cases of HG and thereby low statistical power, one need to be cautious when interpreting the results of this study.

Hyperemesis gravidarum and maternal cancer risk, a Scandinavian nested case-control study.

Reproductive factors have been shown to influence cancer risk. Several pathological conditions during pregnancy have also been associated with subsequent altered cancer risk in the mother. Hyperemesis gravidarum (hyperemesis) is an early pregnancy condition characterized by severe nausea and vomiting resulting in weight loss and metabolic disturbances. Studies have reported associations between hyperemesis and cancer, but results are inconsistent. In this nested case-control study we linked the population-based medical birth registries and cancer registries in Norway, Sweden and Denmark in order to examine overall cancer risk and risk of specific cancer types in women with a history of hyperemesis, using conditional logistic regression. In total, 168,501 cases of cancer in addition to up to 10 cancer-free controls per case were randomly sampled, matched on year of birth and birth registry (n = 1,721,626). Hyperemesis was defined through the International Classification of Diseases. Analyses were adjusted for potential confounders. Hyperemesis was inversely associated with overall cancer risk with adjusted relative risk (aRR) of 0.93 (95% CI: 0.88-0.99), with cancer in the lungs (aRR: 0.60, 95% CI: 0.44-0.81), cervix (aRR: 0.66, 95% CI: 0.49-0.91) and rectum (aRR: 0.48, 95% CI: 0.29-0.78). Thyroid cancer was positively associated with hyperemesis (aRR 1.45, 95% CI: 1.06-1.99) and risk increased with more than one hyperemetic pregnancy (aRR 1.80, 95% CI: 1.23-2.63). Hormonal factors, in particular human chorionic gonadotropin, are likely to be involved in mediating these effects. This study is the first to systematically address these associations and provides valuable knowledge on potential long-term consequences of hyperemesis.

Hyperemesis gravidarum and risk of cancer in offspring, a Scandinavian registry-based nested case-control study.

BACKGROUND: Hyperemesis gravidarum is a serious condition affecting 0.8-2.3% of pregnant women and can be regarded as a restricted period of famine. Research concerning potential long-term consequences of the condition for the offspring, is limited, but lack of nutrition in-utero has been associated with chronic disease in adulthood, including some cancers. There is growing evidence that several forms of cancer may originate during fetal life. We conducted a large study linking the high-quality population-based medical birth- and cancer registries in Norway, Sweden and Denmark, to explore whether hyperemesis is associated with increased cancer risk in offspring. METHODS: A registry-based nested case-control study. Twelve types of childhood cancer were selected; leukemia, lymphoma, cancer of the central nervous system, testis, bone, ovary, breast, adrenal and thyroid gland, nephroblastoma, hepatoblastoma and retinoblastoma. Conditional logistic regression models were applied to study associations between hyperemesis and risk of childhood cancer, both all types combined and separately. Cancer types with five or more exposed cases were stratified by age at diagnosis. All analysis were adjusted for maternal age, ethnicity and smoking, in addition to the offspring's Apgar score, placental weight and birth weight. Relative risks with 95% confidence intervals were calculated. RESULTS: In total 14,805 cases and approximately ten controls matched on time, country of birth, sex and year of birth per case (147,709) were identified. None of the cancer types, analyzed combined or separately, revealed significant association with hyperemesis. When stratified according to age at diagnosis, we observed a RR 2.13 for lymphoma among adolescents aged 11-20 years ((95% CI 1.14-3.99), after adjustment for maternal ethnicity and maternal age, RR 2.08 (95% CI 1.11-3.90)). The finding was not apparent when a stricter level of statistical significance was applied. CONCLUSIONS: The main finding of this paper is that hyperemesis does not seem to increase cancer risk in offspring. The positive association to lymphoma may be by chance and needs confirmation.

Hyperemesis gravidarum and pregnancy outcomes in the Norwegian Mother and Child Cohort - a cohort study.

BACKGROUND: Hyperemesis gravidarum (HG) characterized by excessive nausea and vomiting in early pregnancy, is reported to be associated with increased risks for low birthweight (LBW), preterm birth (PTB), small-for-gestational-age (SGA) and perinatal death. Conflicting results in previous studies underline the necessity to study HG's potential effect on pregnancy outcomes using large cohorts with valid data on exposure and outcome measures, as well as potential confounders. This study aims to investigate associations between HG and adverse pregnancy outcomes using the Norwegian Mother and Child Cohort Study (MoBa). METHODS: All singleton pregnancies in MoBa from 1998 to 2008 were included. Multivariable regression was used to estimate relative risks, approximated by odds ratios, for PTB, LBW, SGA and perinatal death. Linear regression was applied to assess differences in birthweight and gestational age for children born to women with and without HG. Potential confounders were adjusted for. RESULTS: Altogether, 814 out of 71,468 women (or 1.1%) had HG. In MoBa HG was not associated with PTB, LBW or SGA. Babies born to women with HG were born on average 1 day earlier than those born to women without HG; (-0.97 day (95% confidence intervals (CI): -1.80 - -0.15). There was no difference in birthweight when maternal weight gain was adjusted for; (23.42 grams (95% CI: -56.71 - 9.86). Babies born by women with HG had lower risk for having Apgar score < 7 after 1 minute (crude odds ratio was 0.64 (95% CI: 0.43 - 0.95)). No differences between the groups for Apgar score < 7 after 5 minutes were observed. Time-point for hospitalisation slightly increased differences in gestational age according to maternal HG status. CONCLUSIONS: HG was not associated with adverse pregnancy outcomes. Pregnancies complicated with HG had a slightly shorter gestational length. There was no difference in birth weight according to maternal HG-status. HG was associated with an almost 40% reduced risk for having Apgar score < 7 after 1 minute, but not after 5 minutes. The clinical importance of these statistically significant findings is, however, rather limited.

Long-term cardiovascular morbidity following hyperemesis gravidarum: A Norwegian nationwide cohort study.

OBJECTIVE: To investigate whether exposure to hyperemesis gravidarum (hyperemesis) is associated with subsequent maternal cardiovascular morbidity. DESIGN: Nationwide cohort study. SETTING: Medical Birth Registry of Norway (1967-2002) linked to the nationwide Cardiovascular Disease in Norway project 1994-2009 (CVDNOR) and the Cause of Death Registry. POPULATION: Women in Norway with singleton births from 1967 to 2002, with and without hyperemesis, were followed up with respect to cardiovascular outcomes from 1994 to 2009. METHODS: Cox proportional hazards regression model was applied to estimate hazard ratios (HRs) with 95% confidence interval (CI). MAIN OUTCOME MEASURES: The first hospitalisation due to nonfatal stroke, myocardial infarction or angina pectoris, or cardiovascular death. RESULTS: Among 989 473 women with singleton births, 13 212 (1.3%) suffered from hyperemesis. During follow-up, a total of 43 482 (4.4%) women experienced a cardiovascular event. No association was found between hyperemesis and the risk of a fatal or nonfatal cardiovascular event (adjusted HR 1.08; 95% CI 0.99-1.18). Women with hyperemesis had higher risk of hospitalisation due to angina pectoris (adjusted HR 1.28; 95% CI 1.15-1.44). The risk of cardiovascular death was lower among hyperemetic women in age-adjusted analysis (HR 0.73; 95% CI 0.59-0.91), but the association was no longer significant when adjusting for possible confounders. CONCLUSION: Women with a history of hyperemesis did not have increased risk of a cardiovascular event (nonfatal myocardial infarction or stroke, angina pectoris or cardiovascular death) compared to women without.

Cardiovascular risk profile at the age of 40-45 in women with previous hyperemesis gravidarum or hypertensive disorders in pregnancy: A population-based study.

OBJECTIVE: To assess midlife cardiovascular risk profiles in women with a history of hyperemesis or hypertensive disorders in pregnancy compared to women with none of the studied pregnancy complications. STUDY DESIGN: Population-based study. Cardiovascular risk factors at the age of 40-45 among women with previous singleton births only were studied through linkage of the Norwegian Birth Registry and a Norwegian screening program (the Age 40 Program). MAIN OUTCOME MEASURES: Family history of coronary heart disease, body mass index, smoking, physical activity, systolic and diastolic blood pressure, heart rate, cholesterol, triglycerides, antihypertensive treatment and diabetes. RESULTS: Among 178,231 women participating in the Age 40 Program with previous singleton births; 2140 (1.2%) had experienced hyperemesis and 13,348 (7.5%) hypertensive disorders in pregnancy. Women who had suffered from hyperemesis were less physically active. The differences in mean systolic blood pressure and body mass index were probably clinically irrelevant. In women with a history of hypertensive disorders in pregnancy, systolic and diastolic blood pressure and body mass index were higher, and they were more likely to report diabetes in midlife. Women who had suffered from hyperemesis or hypertensive disorders in pregnancy were less likely to be daily smokers. CONCLUSION: Women with hypertensive disorders in pregnancy seemed to have an unfavorable cardiovascular risk profile in midlife compared to women with uncomplicated pregnancies. In contrast there was no consistent evidence of increased risk subsequent to hyperemesis gravidarum. The proportion of daily smokers was lower in women with either of the two pregnancy complications.

Helicobacter pylori infection and severe hyperemesis gravidarum among immigrant women in Norway: a case-control study.

OBJECTIVE: To study associations between Helicobacter pylori exposure and severe hyperemesis gravidarum (HG) among immigrant women in Norway by exploring IgG seropositivity and H. pylori antigens in faeces. Additionally, we investigated whether cytotoxin-associated gene A product (CagA) and vacuolating cytotoxin A (VacA) seropositivity modulated this association. STUDY DESIGN: An institution-based case-control study among immigrant women in Norway was performed at Ullevål and Akershus University Hospitals in September 2005-December 2007. Blood samples were used to explore IgG, CagA and VacA seropositivity, and faecal samples were used to explore the presence of antigens. Multiple logistic regressions were used to study associations between HG and H. pylori exposure. RESULTS: The sample comprised 170 women: 62 cases and 108 controls. The observed proportion of IgG seropositive women did not differ between cases and controls. Neither IgG seropositivity nor CagA and VacA seropositivity were significantly associated with HG. For IgG positive and CagA and VacA negative women, the crude OR was 1.26 (95% CI: 0.57-2.82). For those being IgG positive and CagA and VacA positive, the crude OR was 0.82 (0.40-1.68). Adjustment for confounding factors, such as maternal age, body mass index and earlier HG, did not change the results. Additional adjustment for faecal antigens did not change the conclusions regarding these associations. Likewise, the crude OR for H. pylori antigens was not statistically significant. Adjustment for confounders and IgG seropositivity did not change this result. CONCLUSIONS: This study did not find H. pylori exposure to be significantly associated with severe HG among immigrant women in Norway. This was regardless of whether H. pylori exposure was investigated by IgG seropositivity, CagA and VacA seropositivity or by the presence of H. pylori antigens in faeces. These results may indicate that the association between H. pylori and HG is weaker than previously expected, particularly in populations with high prevalence of H. pylori infection.