Temporal trends in age at menarche and age at menopause: a population study of 312 656 women in Norway

STUDY QUESTION

Have mean age at menarche or mean age at natural menopause changed from the 1939 birth cohort to the 1964 birth cohort?

SUMMARY ANSWER

We estimated a minor decrease in mean age at menarche and an increase by nearly 3 years in mean age at natural menopause.

WHAT IS KNOWN ALREADY

In the Western world, age at menarche decreased across birth cohorts from the early 1800s until the 1950s. Whether mean age at menarche has continued to decrease in birth cohorts after the 1950s remains uncertain. It is also uncertain whether mean age at natural menopause has changed across birth cohorts.

STUDY DESIGN, SIZE, DURATION

We performed a retrospective population study of 312 656 women who were born in Norway during the years 1936–1964.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The data were obtained by two self-administered questionnaires from women who participated in the Norwegian breast cancer screening program (BreastScreen Norway) during the years 2006–2014. We used flexible parametric survival models with restricted cubic splines to estimate mean age at menarche, mean age at menopause and mean number of years between menarche and menopause according to the women’s year of birth. The women who were still having menstrual periods contributed with follow-up time until the time of data collection, and the women who had reported surgical removal of the uterus and/or both ovaries prior to natural menopause contributed with follow-up time until the time of surgery.

MAIN RESULTS AND THE ROLE OF CHANCE

The mean age at menarche was 13.42 years (95% CI: 13.40–13.44 years) among women born during 1936–1939, and it was 13.24 years (95% CI: 13.22–13.25 years) among women born during 1960–1964. The mean age at natural menopause increased from 50.31 years (95% CI: 50.25–50.37 years) among women born during 1936–1939 to 52.73 years (95% CI: 52.64–52.82 years) among women born during 1960–1964. The mean number of years between menarche and menopause increased from 36.83 years (95% CI: 36.77–36.89 years) to 40.22 years (95% CI: 40.11–40.34 years).

LIMITATIONS, REASONS FOR CAUTION

Information about age at menarche and age at menopause was based on self-reports.

WIDER IMPLICATIONS OF THE FINDINGS

Late menopause is associated with increased risk of breast cancer but also with increased life expectancy. Thus, higher mean age at menopause may partly explain the increase in breast cancer incidence after menopause and the increase in life expectancy in recent time. Also, a longer interval between menarche and menopause could suggest that the number of years of female fecundity has increased.

STUDY FUNDING/COMPETING INTEREST(S)

This work was funded by the South-Eastern Norway Regional Health Authority [grant number 2016112 to M.S.G.] and by the Norwegian Cancer Society [grant number 6863294-2015 to E.K.B.]. The authors declare no conflicts of interest.

The relation of age at menarche with age at natural menopause: a population study of 336 788 women in Norway

STUDY QUESTION

Is age at menarche associated with age at menopause or with duration of the reproductive period (interval between menarche and menopause)?

SUMMARY ANSWER

The association of age at menarche with age at menopause was weak and non-linear, and the duration of the reproductive period decreased by increasing age at menarche.

WHAT IS KNOWN ALREADY

It remains uncertain whether age at menarche is associated with age at menopause. Some studies report that women with early menarche also have early menopause. Other studies report that women with early menarche have late menopause, or they report no association. The duration of the reproductive period may be an indicator of the cumulative endogenous exposure to estrogens and progestogens during life course and is associated with risk of breast cancer and endometrial cancer.

STUDY DESIGN, SIZE, DURATION

A retrospective cohort study of 336 788 women, aged 48-71 years, in the BreastScreen Norway during the years 2006-2014 was performed.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Information about age at menarche and menopausal status was obtained by self-administered questionnaires. We used time to event approaches to estimate the associations.

MAIN RESULTS AND THE ROLE OF CHANCE

Median age at menopause was 51 years in most menarche groups. Women with menarche at age 16 years or age ≥ 17 years had menopause 1 year later [median: 52 years, interquartile range (IQR): 49-54 years] than women with menarche at age 13 years (median: 51 years, IQR: 49-54 years, reference) (crude hazard ratio (HR) = 0.95; 95% CI: 0.93-0.97 and 0.95; 95% CI: 0.92-0.99, Pnon-linearity < 0.001). The reproductive period decreased with increasing age at menarche (Pnon-linearity < 0.001), and women with menarche at age ≤ 9 years had 9 years longer median reproductive period than women with menarche at age ≥ 17 years (median: 43 versus 34 years). Adjustment for year of birth did not change the HR estimates notably.

LARGE SCALE DATA

Not applicable.

LIMITATIONS, REASONS FOR CAUTION

Information about age at menarche and age at menopause was based on self-reports. Particularly for age at menarche, the long time interval between the event and data collection may have caused imprecise reporting.

WIDER IMPLICATIONS OF THE FINDINGS

Our study suggests that age at menarche is a strong indicator for the duration of women's reproductive period. Our findings should encourage studies of the independent role of duration of the reproductive period on the risk of breast cancer and endometrial cancer, since these cancers have been associated with exposure to estrogens and progestogens.

STUDY FUNDING/COMPETING INTEREST(S)

The present study was funded by the Norwegian Cancer Society [Grant number 6863294-2015]. The authors declare no conflicts of interest.

Maternal hCG concentrations in early IVF pregnancies: associations with number of cells in the Day 2 embryo and oocytes retrieved

STUDY QUESTION

Do number of cells in the transferred cleavage stage embryo and number of oocytes retrieved for IVF influence maternal hCG concentrations in early pregnancies?

SUMMARY ANSWER

Compared with transfer of a 2-cell embryo, transfer of a 4-cell embryo results in higher hCG concentrations on Day 12 after transfer, and more than 20 oocytes retrieved were associated with low hCG concentrations.

WHAT IS KNOWN ALREADY

Maternal hCG concentration in very early pregnancy varies considerably among women, but is likely to be an indicator of time since implantation of the embryo into the endometrium, in addition to number and function of trophoblast cells.

STUDY DESIGN, SIZE, DURATION

We followed 1047 pregnancies after IVF/ICSI from oocyte retrieval until Day 12 after embryo transfer. Women were recruited in Norway during the years 2005-2013.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Successful pregnancies after transfer of one single embryo that had been cultured for 2 days were included. Maternal hCG was quantified on Day 12 after embryo transfer by chemiluminescence immunoassay, which measures intact hCG and the free β-hCG chain. Information on a successful pregnancy, defined as birth after >16 weeks, was obtained by linkage to the Medical Birth Registry of Norway.

MAIN RESULTS AND THE ROLE OF CHANCE

Transfer of a 4-cell embryo resulted in higher maternal hCG concentrations compared with transfer of a 2-cell embryo (134.8 versus 87.8 IU/l, P < 0.05). A high number of oocytes retrieved (>20) was associated with low hCG concentrations (P < 0.05).

LIMITATIONS, REASONS FOR CAUTION

The factors studied explain a limited part of the total variation of hCG concentrations in early pregnancy. Although embryo transfer was performed at the same time after fertilization, we do not know the exact time of implantation. A further limitation to our study is that the number of pregnancies after transfer of a 2-cell embryo was small (27 cases).

WIDER IMPLICATIONS OF THE FINDINGS

Number of cells in the transferred embryo and number of oocytes retrieved may influence the conditions and timing for embryo implantation in different ways and thereby influence maternal hCG concentrations. Such knowledge may be important for interpretation of hCG concentrations in early pregnancy.

The prevalence of pre-eclampsia in migrant relative to native Norwegian women: a population-based study

OBJECTIVE

To compare the prevalence of pre-eclampsia in migrant women with Norwegian women, and to study the prevalence of pre-eclampsia by length of residence in Norway.

DESIGN

Observational study.

SETTING

The Medical Birth Registry of Norway.

POPULATION

All Norwegian, Pakistani, Vietnamese, Somali, Sri Lankan, Filipino, Iraqi, Thai and Afghan women who gave birth after 20 weeks of gestation during the period 1986-2005 in Norway.

METHODS

The prevalence of pre-eclampsia was calculated by country of birth. The association of country of birth and length of residence in Norway with pre-eclampsia was estimated as the odds ratio (OR) with 95% confidence interval (CI), using Norwegian women as a reference. We made adjustments for maternal age, parity, multifetal pregnancy, year of delivery and maternal diabetes in multivariable analysis.

MAIN OUTCOME MEASURE

Pre-eclampsia.

RESULTS

Migrant women had a lower prevalence of pre-eclampsia than Norwegian women (2.7% versus 3.7%, P < 0.001). Vietnamese (OR, 0.36; CI, 0.29-0.45), Afghan (OR, 0.52; CI, 0.30-0.90) and Thai (OR, 0.57; CI, 0.45-0.73) women had the lowest risk of pre-eclampsia relative to Norwegian women. Adjustment for the variables above or separate analyses for nulliparous women did not change the estimates notably. Using Norwegian women as the reference, the risk of pre-eclampsia increased by length of residence for migrant women: adjusted OR of 0.64 (0.59-0.70) at <5 years and 0.91 (0.84-0.99) at ≥5 years of residence.

CONCLUSIONS

The risk of pre-eclampsia was lower in migrants relative to Norwegian women, but increased by length of residence in Norway.

Concentrations of human chorionic gonadotrophin in very early pregnancy and subsequent pre-eclampsia: a cohort study

STUDY QUESTION

Are low serum concentrations of human chorionic gonadotrophin (hCG) in very early pregnancy associated with pre-eclampsia risk?

SUMMARY ANSWER

Low hCG concentrations in very early pregnancy are associated with increased risk of severe pre-eclampsia.

WHAT IS KNOWN ALREADY

Low maternal serum concentrations of hCG early in pregnancy may indicate impaired proliferation or invasion of trophoblast cells, and thus low hCG concentrations may serve as a marker for impaired placental development. Impaired placental development is assumed to be a cause of pre-eclampsia, but there is little prospective evidence to support this hypothesis.

STUDY DESIGN, SIZE, DURATION

We performed a prospective cohort study of pregnancies after IVF at Oslo University Hospital 1996-2010 with linkage to the Medical Birth Registry of Norway to obtain information on pre-eclampsia development.

PARTICIPANTS/MATERIALS, SETTING, METHODS

We included 2405 consecutive singleton pregnancies and examined the association of maternal serum hCG concentrations (measured using Elecsys, Roche) on Day 12 after embryo transfer with the risk of any pre-eclampsia and of mild and severe pre-eclampsia.

MAIN RESULTS AND THE ROLE OF CHANCE

HCG concentrations were inversely associated with pre-eclampsia risk in a dose-dependent manner (Ptrend 0.02). Compared with women with hCG ≥150 IU/l, women with hCG <50 IU/l were at 2-fold higher overall risk of pre-eclampsia [absolute risk 6.4 versus 2.8%; odds ratio (OR) 2.3, 95% confidence interval (CI) 1.2-4.7]. The inverse association was restricted to severe pre-eclampsia (Ptrend 0.01), thus, women with hCG <50 IU/l were at 4-fold higher risk of severe pre-eclampsia than women with hCG ≥150 IU/l (absolute risk 3.6 versus 0.9%; OR 4.2, 95% CI 1.4-12.2). For mild pre-eclampsia, there was no corresponding association (Ptrend 0.36).

LIMITATIONS, REASONS FOR CAUTION

Results for IVF pregnancies may not be generalizable to spontaneously conceived pregnancies.

WIDER IMPLICATIONS OF THE FINDINGS

Plausible causes of low maternal hCG concentrations very early in pregnancy include impaired placental development and delayed implantation. Thus, these results provide prospective evidence to support the hypothesis that impaired placental development may be associated with subsequent development of severe pre-eclampsia.

STUDY FUNDING/COMPETING INTEREST

The study was financially supported by the Research Council of Norway. None of the authors has any conflict of interest to declare.

Is unilateral oophorectomy associated with age at menopause? A population study (the HUNT2 Survey)

STUDY QUESTION

Is unilateral oophorectomy associated with age at menopause?

SUMMARY ANSWER

Women who had undergone unilateral oophorectomy entered menopause 1 year earlier than women with two ovaries intact.

WHAT IS ALREADY KNOWN

There is substantial variation in age at natural menopause. Unilateral oophorectomy implies a significant reduction of the ovarian follicular reserve. Thus, one might expect that the time to menopause is shortened by several years in women who have undergone unilateral oophorectomy.

STUDY DESIGN, SIZE AND DURATION

A retrospective cohort study of 23 580 Norwegian women who were included in the population-based HUNT2 Survey during the years 1995-1997.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Data were obtained by two self-administered questionnaires at study inclusion. Cox proportional hazard models were used to estimate relative risks of menopause according to unilateral oophorectomy status with and without adjustment for birth cohort, parity, smoking, body mass index (BMI) and age at menarche.

MAIN RESULTS AND THE ROLE OF CHANCE

Women who had undergone unilateral oophorectomy were younger at menopause [mean 49.6 years; 95% confidence interval (CI): 49.2-50.0] than women without unilateral oophorectomy (mean 50.7 years; 95% CI: 50.6-50.8) (P < 0.001). The crude relative risk of menopause was 1.28 (95% CI: 1.15-1.42) and remained similar after adjustment for the study factors above (adjusted relative risk 1.27; 95% CI: 1.14-1.41). In addition, recent birth cohort and high BMI were associated with higher age at menopause.

LIMITATIONS, REASONS FOR CAUTION

Information on unilateral oophorectomy was based on self-reports. Some women may therefore have been misclassified.

WIDER IMPLICATIONS OF THE FINDINGS

Although the effect of unilateral oophorectomy on the age at menopause is similar to that of smoking, it is weaker than anticipated from the loss of ovarian follicular reserve. Thus, compensatory mechanisms may occur in the remaining ovary.

Paternal age, placental weight and placental to birthweight ratio: a population-based study of 590,835 pregnancies

STUDY QUESTION

Is the age of the father associated with placental weight or the ratio of placental weight to birthweight?

SUMMARY ANSWER

Placental weight and placental to birthweight ratio increased according to increasing paternal age, also after adjustment for maternal age.

WHAT IS KNOWN ALREADY

High paternal age and also high placental to birthweight ratio have been associated with adverse pregnancy outcome.

STUDY DESIGN, SIZE AND DURATION

We performed a population-based study and included all singleton births after 22 weeks of gestation in the Medical Birth Registry of Norway (n = 590,835) during the years 1999-2009.

PARTICIPANTS/MATERIALS, SETTING, METHODS

We compared mean placental weight and placental to birthweight ratio between paternal age groups. The association of paternal age with placental weight was estimated by linear regression analyses, and adjustments were made for maternal age, birthweight, parity, offspring sex, gestational age at birth, maternal smoking, pre-eclampsia, maternal diabetes mellitus and pregnancy after assisted reproductive technology (ART).

MAIN RESULTS AND THE ROLE OF CHANCE

In pregnancies with fathers aged 20-24 years old, the mean placental weight was 656.2 g [standard deviation (SD) 142.8], whereas it was 677.8 g (SD 160.0) in pregnancies with fathers aged 50 years or older (P < 0.001). The mean offspring birthweight in pregnancies with fathers aged 20-24 year old was 3465.0 g (SD 583.8), and it was 3498.9 g (SD 621.8) when the father was 50 years or older (P < 0.001). The placental to birthweight ratio in the corresponding paternal age groups were 0.191 (SD 0.039) and 0.196 (SD 0.044) (P < 0.001). In multivariable linear regression analysis the placentas in pregnancies fathered by a man of 50 years or older were estimated to weigh 13.99 g [95% confidence interval (CI) 10.88-17.10] more than in pregnancies with a 20-24-year-old father (P < 0.001) after adjustment for maternal age, birthweight, parity, offspring sex, gestational age at birth, maternal smoking, pre-eclampsia, maternal diabetes mellitus and pregnancy after ART.

LIMITATIONS, REASONS FOR CAUTION

Paternal age explains only a small proportion of the total variation in placental weight.

WIDER IMPLICATIONS OF THE FINDINGS

Our findings may increase the understanding of the father's role in human pregnancy.

STUDY FUNDING/ COMPETING INTEREST(S)

Norwegian Resource Centre for Women's Health, Norway. No conflict of interest.

TRIAL REGISTRATION NUMBER

N/A.

Psychological Distress, Coping, and Disease Progression in HIV-positive Homosexual Men

The objectives of the study were (1) to examine the role of coping styles in disease progression in models controlling for initial CD4+ cell counts, distress, and health behavior in a sample of HIV- positive homosexual men (n = 65), and (2) to investigate the relationship between coping styles and distress (e.g. depression, anxiety, negative ruminations). A consistent association between planful problem-solving coping and disease progression was demonstrated. Distress was positively correlated with indicators of passive-defensive coping style (e.g. self- controlling, escape-avoidance), and negatively correlated with planful problem-solving and positive reappraisal. The results suggest that coping styles may merit a specific focus in future research of psychological factors in HIV infection, particularly as they may relate both to medical outcome and to the social/emotional aspects of being HIV-infected.

Serum long chain n-3 fatty acids (EPA and DHA) in the pregnant mother are independent of risk of type 1 diabetes in the offspring

BACKGROUND

This article aims to study whether higher proportions of the long chain n-3 fatty acids eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA) in the phospholipid fraction of serum samples in pregnancy were associated with a lower risk of childhood onset type 1 diabetes in the offspring.

METHODS

In a prospective cohort of nearly 30 000 pregnant women who gave birth in Norway during 1992-1994, we analysed serum samples from 89 women whose child developed type 1 diabetes and was included in the nationwide Norwegian Childhood Diabetes Registry and 125 randomly selected women whose child did not develop type 1 diabetes before 15 years of age. Specific fatty acids were expressed as the proportion of total fatty acids (g/100 g) in the phospholipid fraction in serum analysed using solid phase extraction and gas chromatography with flame ionization detection.

RESULTS

There was no significant association between EPA or DHA in maternal serum and risk of type 1 diabetes in the offspring. Odds ratio (OR) for upper versus lower quartile of EPA was 0.75 [95% confidence interval (CI) 0.34-1.65], test for trend p = 0.4, and for DHA OR = 0.71 (95% CI 0.33-1.53), test for trend p = 0.6. No significant association was found for the sum of n-3 fatty acids, or for n-6/n-3 ratio in the mother with risk of type 1 diabetes in the offspring.

CONCLUSIONS

Our data did not support the hypothesis that higher proportions of maternal EPA or DHA during pregnancy are associated with a lower risk of type 1 diabetes in the offspring.

Placental weight and excess postpartum haemorrhage: a population study of 308,717 pregnancies

OBJECTIVE

To investigate whether placental weight may be positively associated with the prevalence of excess postpartum haemorrhage because large placentas have large surface areas.

DESIGN

Registry-based cross-sectional study.

SETTING

Population study.

POPULATION

All singleton deliveries after 21 weeks of gestation in Norway during 1999-2004 (n = 308,717).

METHODS

Data were obtained from the Medical Birth Registry of Norway, which is based on compulsory notification of births by the midwife or doctor in charge of the delivery.

MAIN OUTCOME MEASURE

Excess postpartum haemorrhage was defined as bleeding of 500 ml or more within 2 hours of delivery.

RESULTS

There was a gradual increase in the prevalence of excess postpartum haemorrhage with increasing placental weight (test for trend, P < 0.05). Having a placenta of 1100 g or more was associated with 2.5 times (odds ratio 2.54, 95% CI 2.31-2.79) higher prevalence than having a placenta of 300-499 g, after adjustment for offspring birthweight, parity, caesarean section and placenta-related and delivery-related complications. A large placenta relative to birthweight was also associated with higher prevalence of excess postpartum haemorrhage.

CONCLUSION

The size of the placental surface may explain the positive association of placental weight with the prevalence of postpartum haemorrhage. In pregnancies with a large placenta relative to offspring birthweight, other factors that enhance bleeding may also play a role.

Maternal human parvovirus B19 infection and the risk of fetal death and low birthweight: a case-control study within 35 940 pregnant women

OBJECTIVES

To assess the association between maternal parvovirus B19 infection and fetal death, birthweight and length of gestation.

DESIGN

Case-control study.

SETTING

Population based.

POPULATION

Cases were all 281 women with fetal death within a cohort of 35 940 pregnant woxmen in Norway. The control group consisted of a random sample of 957 women with a live born child.

METHOD

Information on pregnancy outcome was obtained from the Medical Birth Registry of Norway. First trimester serum samples were tested for antibodies against parvovirus B19 (IgM and IgG). In seronegative women, further serum was analysed to detect seroconversion during pregnancy.

MAIN OUTCOME MEASURES

Fetal death, length of gestation and birthweight.

RESULTS

Two of 281 (0.7%) of the women who experienced fetal death and nine of 957 (0.9%) of the controls had presence of IgM antibodies, crude odds ratio 0.8; 95% CI (0.2-3.5). In initially, seronegative women, 3.1% (2/65) with fetal death and 2.6% (8/307) with a live birth seroconverted, crude odds ratio 1.2; 95% CI (0.2-5.7). Presence of maternal parvovirus-specific IgG or IgM antibodies in the first trimester, or seroconversion during pregnancy were not associated with lower birthweight or reduced length of gestation in live born children, but was associated with low birthweight in stillborn offspring.

CONCLUSION

Maternal parvovirus B19 infection was not associated with fetal death in our study. Very few cases of fetal death may be attributed to maternal parvovirus B19 infection.

Drug use in pregnancy among parous Scandinavian women

 SUMMARYThe aim of the present study was to investigate the prevalence of drug use in 1945 parous pregnant Scandinavianwomen, to determine the most common drug categories, and to describe changes in drug use throughoutpregnancy. The women were interviewed about drug use by a specially trained midwife at five different occasionsduring pregnancy: at gestational week 17, 25, 33, 37, and on admission for delivery at three Scandinavianstudy sites (Trondheim, Bergen and Uppsala). When excluding vitamins and iron supplementation, 1086(56%) women reported at least one episode of drug use during pregnancy, with an average of 2.6 episodesamong the women reporting drug use. Four percent of the women accounted for 18% of the episodes of druguse. Systemic anti-infectives (15%), respiratory drugs (12%), gastrointestinal drugs (11%) and analgesics(11%) were the most widely used drugs among all the pregnant women. The number of women using drugsincreased throughout pregnancy. NORSK SAMMENDRAGHensikt med studien var å undersøke forekomsten av legemiddelbruk hos 1945 annen- eller tredjegangs fødendeskandinaviske kvinner, å beskrive hvilke legemiddelgrupper som ble hyppigst brukt, og å beskrive hvordanlegemiddelbruken forandrer seg i løpet av svangerskapet. Kvinnene ble intervjuet av en spesialopplært jordmorved fem tidspunkt under svangerskapet: ved gestasjonsuke 17, 25, 33, 37 og ved innleggelse før fødselenpå tre skandinaviske studiesteder (Trondheim, Bergen and Uppsala). Når jern- og vitamintilskudd ekskluderes,hadde 1086 (56%) av de gravide minst en episode av legemiddelbruk under svangerskapet, med et gjennomsnittpå 2,6 episoder blant kvinnene som rapporterte legemiddelbruk. Fire prosent av de gravide stod for 18%av episodene med legemiddelbruk. Systemiske antiinfektiva (15%), legemidler med virkning på respirasjonssystemet(12%), gastrointestinale legemidler (11%) og analgetika (11%) var de hyppigst brukte legemiddelgruppene.Andel gravide som rapporterte legemiddelbruk økte i løpet av svangerskapet.

The impact of BMI on subgroups of uterine cancer

Background:

Obesity increases the risk of uterine cancer, but results by histological type have differed.

Methods:

We followed 36 755 women for 17.8 years for uterine cancers.

Results and conclusion:

Body mass index (BMI) was positively associated with uterine cancers as a whole, particularly for endometrioid adenocarcinomas, for which the relative risk for very obese women (BMI: ⩾40 kg m⁻²) compared with lean (BMI: 20–24 kg m⁻²) women, was 11.1 (95% confidence interval: 5.2–23.8).

Impaired weight gain predicts risk of late death after surgery for congenital heart defects

OBJECTIVES

To describe long-term somatic growth in terms of weight for age in children operated on for congenital heart defects who die late (after the first 30 postoperative days) and to study the relationship between postoperative weight gain and survival after surgery for congenital heart defects.

METHODS

This was a nested case-control study of 80 children born in 1990-2002 who died late after surgery for congenital heart defects at Rikshospitalet, Norway. Weight data were obtained for 74 children, of whom 31 with no extra-cardiac anomalies were defined as cases and 31 surviving children with similar surgical complexity were defined as controls.

RESULTS

In the 74 children who died late, mean weight for age converted to z scores at birth, at last operation and at last recorded weight were 0.12, -1.31 and -2.09. In the 31 children defined as cases, the same weight z scores were 0.07, -1.21 and -2.01 compared with 0.05, -1.10 and -0.99 in the 31 matched controls. The odds ratio (OR) for death was 13.5 (95% CI 3.6 to 51.0) if there was a decrease in weight z score of >0.67 after the last operation. Median follow-up time after operation was 5.7 months.

CONCLUSIONS

A decrease in weight for age during the first months after surgery for congenital heart defects of more than 0.67 z scores, corresponding to a downward percentile crossing through at least one of the displayed percentile lines on standard growth charts, is strongly related to late mortality in children operated on for congenital heart defects.

A short matrix-version of the Edinburgh Depression Scale

OBJECTIVE

Given the importance of depression as a world health problem, depression assessment should be standard practice in large-scale health surveys. The aim of the study was to construct a short matrix-version of the Edinburgh Depression Scale (EDS) that can be used in questionnaire studies.

METHOD

On the basis of the complete EDS scale of ten items, answered by 2730 women, stepwise multiple regression analysis was used to find the combination of items that explains the maximum proportion of the variance of the full scale sum score. The selected EDS items were thereafter correlated with the Hopkins Symptom Check List (SCL-25) for external validation.

RESULTS

The sum of five selected items from the EDS correlated at r = 0.96 with the full version. The EDS-5 scores correlated strongly with the SCL-25 (r = 0.75).

CONCLUSION

The EDS-5 version shows good psychometric properties and may, for some scientific purposes, substitute the full EDS scale.

Depression during pregnancy and after delivery: a repeated measurement study

The aim of this study was to examine the risk of depression in the postpartum period (first four months after delivery) as compared to the remaining postnatal year and the pregnancy period. All postpartum women from two municipalities in Norway were included in a questionnaire study of mental health (n = 416). Over 50% of the women (n = 259) answered an identical questionnaire at an additional time either before or after the postpartum period. The level of depression was measured by the Edinburgh Postnatal Depression Scale (EPDS) and the Hopkins Symptom Check List-25 items (SCL-25). The point prevalence of depression (EPDS> or =10) in the first four months postpartum did not differ significantly as compared to other time periods during pregnancy and the postnatal year. This finding remained also after controlling for other risk factors of depression; high score on the life event scale, prior depression and poor partner relationship. There was a non-significant trend of lower prevalence of depression during early pregnancy and after the first eight postnatal months. In conclusion, our findings suggest that the first four months postpartum were not distinguished by higher depression prevalence as compared to other time periods during pregnancy and the first postnatal year.

Guidelines for iron supplementation in pregnancy: compliance among 431 parous Scandinavian women

OBJECTIVE

The need for iron in pregnancy is rarely met by dietary food intake alone. Therefore, guidelines on iron supplementation have been developed to ensure optimal maternal and foetal iron provision. Today, the World Health Organization recommends iron supplementation during the second half of pregnancy. Our aim was to study compliance to these guidelines among 431 parous Scandinavian women. In addition, the association between maternal socio-demographic and lifestyle factors, maternal haemoglobin (Hb) values and non-compliance was assessed.

METHODS

The women were interviewed about iron use at gestational weeks 25, 33 and 37 at the three Scandinavian study sites, Trondheim, Bergen and Uppsala.

RESULTS

In all, 27% of the women used iron supplements continuously during the second half of pregnancy, hence complying with the guidelines. Further, 41% of the women reported periodical and 32% no use of iron supplementation during the second half of pregnancy. In the multivariable analyses, high Hb-concentration, living in Uppsala [OR: 3.1 (1.6-6.0)] or Bergen [OR: 4.7 (2.4-9.3)] as opposed to Trondheim, and smoking during pregnancy [OR: 2.0 (1.1-3.5)] were associated with non-compliance to guidelines.

CONCLUSION

We conclude that maternal Hb values, demographic factors and smoking during pregnancy are among the factors associated with non-compliance to guidelines on iron supplementation during pregnancy.

Depression in postpartum and non-postpartum women: prevalence and risk factors

OBJECTIVE

The aim of the study was to assess the prevalence of depression in postpartum women as compared with non-postpartum women, and to identify risk factors of depression in both groups.

METHOD

A population based questionnaire study was performed among women 18-40 years in two municipalities in Norway in 1998-1999. A total of 2,730 women were included, of whom 416 were in the postpartum period.

RESULTS

The prevalence of depression was higher in non-postpartum as compared with postpartum women. High scores on the life event scale, a history of depression and a poor relationship to the partner were associated with depression in both postpartum and non-postpartum women. When controlling for the identified risk factors of depression the odds-ratio for depression in the postpartum period was 1.6 (95% CI: 1.0-2.6).

CONCLUSION

The risk for depression was increased in the postpartum period, when controlling for the uneven distribution of risk factors.

Changing paternity and time since last pregnancy; the impact on pre-eclampsia risk. A study of 547 238 women with and without previous pre-eclampsia

BACKGROUND

Long time interval between pregnancies has been found to increase the risk of pre-eclampsia in second pregnancy. Our aim was to investigate whether this effect is influenced by a history of pre-eclampsia or a change in paternity.

METHODS

We studied 547 238 women with a first and second pregnancy registered in the Medical Birth Registry of Norway, 1967-1998. The relative risk of pre-eclampsia in the second delivery according to time interval between deliveries was estimated as odds ratios (OR) in logistic regression models, controlling for changing paternity, maternal age and calendar time period in women with and without previous pre-eclampsia.

RESULTS

A change of paternity for the second pregnancy was associated with a reduced risk of pre-eclampsia after controlling for the time since first delivery (adjusted OR = 0.80, 95% CI : 0.72-0.90), but the interaction between change in paternity and time between deliveries was significant only for women with no previous pre-eclampsia. The interaction between history of pre-eclampsia and time interval between the two deliveries was highly significant, and for women with no previous pre-eclampsia the risk of pre-eclampsia in second pregnancy increased with increasing time interval (for intervals longer than 15 years the adjusted OR was 2.11, 95% CI : 1.75-2.53). For women with previous pre-eclampsia the risk tended to decrease with increasing time interval between deliveries.

CONCLUSIONS

The protective impact of a new father for the second pregnancy challenges the hypothesis of primipaternity, and implies that the increase in pre-eclampsia risk ascribed to new father by others is due to insufficient control for interpregnancy interval.

Seasonal variation in the occurrence of pre-eclampsia

OBJECTIVE

To obtain evidence for seasonal variability in pre-eclampsia using the assumption that environmental factors may have a role in the causal mechanisms.

DESIGN

Cross sectional population-based study.

POPULATION

All 1,869,388 deliveries in Norway in the years 1967 to 1998.

METHOD

For each month, the percentage of births complicated by pre-eclampsia was calculated. The relative risks of pre-eclampsia by month of delivery were estimated as odds ratios using the month with lowest risk as the reference category.

RESULTS

Mothers of children born in August had the lowest risk of pre-eclampsia, and the risk was highest in the winter months (for December adjusted OR: 1.26, 95% CI 1.20-1.31). This pattern was independent of parity. maternal age, year and place of living.

CONCLUSION

The finding may provide a new clue for understanding the causes of pre-eclampsia. Environmental factors that show a similar seasonal variation should be investigated as possible causes.

Gender differences in syringe exchange program use in Oslo, Norway

AIMS

To examine gender differences in syringe exchange program (SEP) use, particularly frequent SEP use, within and across survey years.

DESIGN

Three consecutive, anonymous cross-sectional surveys.

SETTING

The SEP in Oslo, Norway.

PARTICIPANTS

Two hundred and eighty-eight, 449 and 523 SEP participants interviewed during comparable 1-week periods in 1992, 1994 and 1997, respectively.

MEASUREMENTS

Brief structured questionnaires assessed SEP use, HIV risk behaviors and self-reported HIV status. Chi square statistics, t-tests and analysis of variance were used to identify gender differences; logistic regression was used to identify independent correlates of frequent SEP use.

FINDINGS

Women reported injecting more frequently than men, but neither reported more frequent SEP use nor acquiring more syringes during an exchange. Although syringe sharing decreased significantly over time, in 1997, 51% of SEP participants continued to share. HIV prevalence remained low (3-5%) over time. After controlling for gender, age and HIV risk factors, frequent SEP use was significantly correlated with frequent injection for both women (OR = 1.4) and men (OR = 1.5). A lack of income or benefits independently increased the likelihood of being a frequent SEP user (OR = 3.0), while having shared a syringe at last injection independently decreased this likelihood (OR = 0.5).

CONCLUSIONS

Gender was not associated with frequent SEP use; rather, the single most important correlate of frequent SEP use was injection frequency. Women's need for sterile syringes may not be fully addressed, despite the existence of a well-established and well-utilized SEP.

Is preeclampsia an infectious disease?

BACKGROUND

Studies have suggested a strong paternal factor in the etiology of preeclampsia. If preeclampsia is caused by an infectious agent transmitted by the woman's partner, seronegative women who may experience primary infection in pregnancy should be at increased risk of preeclampsia as compared to previously infected women. The aim of this study was to assess the impact of being seronegative for some viruses transmitted by close contact on the risk of developing preeclampsia.

METHODS

Nine hundred and seventy-eight women were randomly drawn from a basic study population of 35,940 pregnant women in Norway. A serum sample drawn at the first antenatal visit was analyzed for specific IgG antibodies against herpes simplex virus type-2, cytomegalovirus and Epstein-Barr virus. For comparison, antibody status against Toxoplasma gondii was also assessed. Information on preeclampsia in pregnancy was obtained through linkage to the Medical Birth Registry of Norway.

RESULTS

Thirty-three (3%) women developed preeclampsia. The risk of developing preeclampsia seemed to be increased for women who were seronegative for the viruses studied. Seronegativity for Toxoplasma gondii did not show such a pattern.

INTERPRETATION

Women who are seronegative for antibodies against viral agents transmitted through close contact seem more likely to develop preeclampsia. This finding indicates that women who are seronegative to such agents may acquire primary infection in pregnancy, and subsequently be at increased risk of preeclampsia. This hypothesis could represent a new approach to the causes of preeclampsia, and encourage search for yet unidentified microbes as a possible causal factor.

Review of validation studies of the Edinburgh Postnatal Depression Scale

OBJECTIVE

To review validation studies of the Edinburgh Postnatal Depression Scale (EPDS).

METHOD

A systematic search was performed in Medline and the Science Citation Index Expanded (ISI) from the period 1987-2000. For sensitivity and specificity of the EPDS presented in each study, 95% confidence intervals were estimated. Positive and negative predictive values were estimated assuming prevalences of postpartum depression ranging from 5% to 20%.

RESULTS

Eighteen validation studies were identified. The study design varied between studies. The sensitivity and specificity estimates also varied: 65-100% and 49-100%, respectively. The confidence intervals were estimated to be wide. Our estimates suggest a lower positive predictive value in a normal population than in the validation study samples.

CONCLUSION

Most studies show a high sensitivity of the EPDS. Because of the differences in study design and large confidence intervals, uncertainty remains regarding the comparability between the sensitivity and specificity estimates of the different EPDS versions.

Drug use during early pregnancy. The impact of maternal illness, outcome of prior pregnancies and socio-demographic factors

OBJECTIVE

Socio-demographic factors have been associated with drug use in pregnancy. However, information on maternal illness has rarely been included in previous studies. The aim of this study was therefore to estimate the impact of maternal illness and prior pregnancy outcome on the use of analgesics/antipyretics, anti-infectives and antihistamines in early pregnancy controlling for socio-demographic factors.

METHODS

One thousand nine-hundred and forty-five parous pregnant women from Norway and Sweden were included in an interview study. Information on drug use, obstetric history, maternal illness and socio-demographic factors was collected by specially trained midwives at gestational week 17 and form the basis for the present analyses.

RESULTS

After control for socio-demographic factors, reported illness was associated with the use of analgesics/antipyretics, anti-infectives and antihistamines during early pregnancy. The use of analgesic/antipyretic and anti-infective drugs differed between study sites. Sociodemographic factors such as age, parity, marital status, education, occupation and smoking habits did not influence drug use in the multivariate analysis.

CONCLUSION

Maternal illness during pregnancy was associated with drug use in early pregnancy. When studying factors related to drug use during pregnancy, it is important to include information on maternal illness. Socio-demographic factors may be confounders and lead to erroneous conclusions about the factors related to drug use.

[Geographical variation in the occurrence of induced late abortions in Norway 1996-97]

BACKGROUND

The aims of this study were to assess i) the geographical variation in the prevalence of request for induced abortion after 12th week of pregnancy and ii) the geographical variation in the probability of refusal of abortion request for other reasons than foetal defects.

MATERIAL AND METHODS

All medical records regarding request for induced abortion after 12 weeks of pregnancy during the period 1996-97 in Norway were collected in 1998 by the National Board of Health.

RESULTS

There were a total of 1,061 requests for induced abortion, of whom 41 were withdrawn. 303 requests were based on foetal defects. Of the remaining 717 requests, which were included in the analysis, 144 (20%) were refused. The counties Vest-Agder, Møre og Romsdal and Finnmark had the lowest prevalence of induced abortions after the 12th week of pregnancy (< 4 per 10,000 women, 15-45 years of age, during 1996-97) and Oslo, Buskerud and Sør-Trøndelag had the highest (> 10 per 10,000 women). Hospitals in the south-western part of Norway (Vest-Agder/Aust-Agder/Rogaland) were 7.8 (95% confidence intervall 3.5-17.2) times more likely to refuse the requests as compared to hospitals in Østfold/Oslo/Akershus.

INTERPRETATION

Cultural differences within Norway may explain, though not excuse, the observed geographical differences in the practice of the abortion act.

The Edinburgh Postnatal Depression Scale: validation in a Norwegian community sample

This study was undertaken to validate a Norwegian translation of the Edinburgh Postnatal Depression Scale (EPDS). The EPDS was validated against the DSM-IV criteria for major depression, derived from the PRIME-MD, in an interview study of 56 women selected from a community-based questionnaire study of 310 women 6 weeks postpartum. A score of > or =10 on the EPDS scale identified all women with major depression, giving a sensitivity of 100% (95% confidence interval; 72%-100%) and a specificity of 87% (95% confidence interval; 77%-95%). The EPDS scores were strongly correlated with the Montgomery-Asberg Depression Rating Scale in the subsample of women interviewed (n=56) and with the Hopkins Symptom Check List (SCL-25) scores in the questionnaire study (n=310). Our results with regard to the sensitivity and specificity estimates are comparable with prior validation studies; however, the confidence intervals around the estimates are wide. Nevertheless, this study confirms that the EPDS is a valid clinical screening instrument for detecting postpartum depression.

Herpes simplex virus type-2 antibodies in pregnant women: the impact of the stage of pregnancy

In this study the impact of pregnancy duration on the measured level of HSV-2 antibodies was assessed. The study population comprised 35,940 pregnant women in Norway, in 1992-4, followed during pregnancy. A random sample of 960 women was selected. A mean of 2.6 serum samples from each woman were analysed for HSV-2 specific IgG antibodies at different times in pregnancy. Crude and adjusted odds ratios were estimated in logistic regression models taking all observations per women into account. Twenty-seven percent of the pregnant women had antibodies against HSV-2 in the first trimester. The adjusted odds ratio of being HSV-2 antibody positive decreased during the pregnancy and was 0.5 (0.2-0.9, 95% confidence interval) in the 40th as compared to the 10th week of pregnancy. About 50% of initially HSV-2 positive women did not have detecable antibodies by the end of the pregnancy. This may be explained by haemodilution during pregnancy. Our findings have diagnostic implications and should encourage further studies.

[Postnatal care--sleep, rest and satisfaction]

BACKGROUND

During the last decade most hospitals in Norway have introduced breastfeeding according to the baby's needs during night-time as well. The aim of this study was to examine whether women had sufficient sleep and rest in the maternity unit, and the factors influencing insufficient sleep and rest. The degree of satisfaction with the stay in the maternity unit and factors associated with satisfaction were also studied.

MATERIAL AND METHODS

From April to November 1998, 160 postnatal women in two Norwegian communities were included in a questionnaire-based study, representing 89% of all women eligible for the study.

RESULTS

47% (75/160) of the women reported lack of sleep and rest in the maternity unit. The factor most strongly associated with lack of sleep and rest was not having a single room (adjusted odds ratio 11.0; 95% confidence interval: 1.7-69.1). 56% (88/158) of the women reported to be very satisfied, 39% (68/158) were moderately satisfied, and 5% (8/158) dissatisfied with the stay at the maternity unit. Not being very satisfied was associated with the hospital of delivery (adjusted OR 18.0; 95% CI: 2.2-149.1), and with insufficient sleep and rest (OR 3.3: 1.3-8.1).

INTERPRETATION

Our results suggest that women do not get sufficient sleep and rest under existing circumstances in maternity units.

[Induced abortion because of fetal abnormality in Norway, 1996-7]

BACKGROUND

The objective of this study was to estimate the national and regional rates of induced abortions after the 12th gestational week attributed to fetal maldevelopment in Norway during 1996 and 1997.

MATERIALS AND METHODS

In 1998, the National Board of Health requested from all hospitals copies of relevant documents in the medical records of women who had applied for induced abortion after 12th gestational week.

RESULTS

There were 303 women in 1996 and 1997 who applied for induced abortion because of diagnosed fetal maldevelopment. For all of these women the application was accepted. One woman did not have an abortion. The national rate of induced abortion attributed to fetal maldevelopment was 2.5 per 1000 births. There were regional differences in the rate of abortion. In 53% of all applications for induced abortion the fetal diagnosis was not reported. Among the reported diagnoses, 28% were chromosomal abnormalities.

INTERPRETATION

There is a need for better knowledge of factors influencing the number of induced abortions attributed to fetal malformations. We also need a better understanding of the impact of such abortions on the observed perinatal mortality and occurrence of birth defects.

[Hepatitis C virus infection among pregnant women and their children in Norway]

Estimates indicate the births of 6 to 78 children vertically infected with hepatitis C virus infection each year in Norway. There is insufficient knowledge of the magnitude of this health problem and the National Institute of Public Health commissioned the authors to approach issues relating to vertical transmission of hepatitis C virus (HCV) infection in Norway. The risk of vertical transmission of HCV appears to be associated with the titre of the maternal viral load. Vertical transmission from nonviraemic mothers has not been demonstrated. No postexposure prophylaxis exists. There is a lack of association between vertical HCV transmission and delivery mode and no association with breast feeding. Universal screening for HCV infection among pregnant women is not recommended. Children born to women known to be HCV-positive should be followed up with antibody and polymerase chain reaction investigations in order to clarify their HCV status. More studies of HCV infection among pregnant women and their children in Norway are needed.

[Hepatitis C virus among pregnant women in Norway--occurrence of antibodies and pregnancy outcome]

BACKGROUND

Transmission of hepatitis C virus from mother to child is well documented. The prevalence of antibodies against hepatitis C virus among pregnant women in Norway is however, not known. The aim of this study was to estimate the maternal prevalence of antibodies against hepatitis C virus and to study the association between presence of antibodies and fetal death.

MATERIAL AND METHODS

From a study of 35,940 pregnant women, a random sample of 970 women and all women with fetal death after 16 weeks of gestation (n = 283), were tested for antibodies against hepatitis C virus.

RESULTS

7 out of 970 women in the random sample (0.7%; 0.2-1.3%, 95% confidence interval) had antibodies against hepatitis C virus. The same prevalence (0.7%, 2 out of 283) was found among women with fetal death.

INTERPRETATION

The prevalence of antibodies against hepatitis C virus among Norwegian women was unexpectedly high. Further research is necessary to understand the causes and implications of this observation.

Changes in condom use after HIV diagnosis

We investigated changes in condom use after HIV diagnosis. The study population comprised 78 asymptomatic HIV-infected subjects recruited from a clinic in Oslo, Norway, during 1988-92. In total, 240 follow-up visits were carried out. The response variable was repeated measurements of whether or not condoms were always used during anal/vaginal intercourse at follow-up. The explanatory variables were: time from HIV diagnosis to follow-up, exposure group (heterosexually infected, homosexual men, or infected through injecting drug use), time of HIV diagnosis (before 1987 or later), and history of condom use before HIV diagnosis. Random effects logistic regression analysis was used to study incremental changes in condom use, accommodating an unbalanced repeated measurement design. The use of condoms increased monotonously over time after HIV diagnosis in all exposure groups. Condom use was least likely among injecting drug users, subjects diagnosed before 1987 and subjects without a history of frequent condom use before HIV diagnosis.