Faculty Bibliography

Schizophrenia has been linked to advanced paternal age, but the explanation is unknown. We questioned whether the incidence of schizophrenia would be related to male reproductive capacity, as reflected in the time taken to conceive. We measured the incidence of schizophrenia in relation to time to conception in a sub-group of 12,269 in the Jerusalem cohort whose mothers, interviewed post-partum, reported that the pregnancy had been intended. Compared with those conceived in less than 3 months, the unadjusted relative risks (RR) of schizophrenia associated with conception-waits of 3-5, 6-11 and 12+ months were 1.10 (95% confidence interval, 0.62-1.94), 1.41 (0.79-2.52) and 1.88 (1.05-3.37) with p for trend=0.035. This trend was attenuated somewhat by adjusting for paternal age, and was observed more strongly in offspring of fathers aged 30+ (p=.010). These findings suggest that factors associated with fecundability, either male or female, may contribute to the risk of schizophrenia

Some forms of epigenetic abnormalities transmitted to offspring are manifested in differences in disease incidence that depend on parent-of-origin. To explore whether such phenomena might operate in schizophrenia spectrum disorders, we estimated the relative incidence of these conditions in relation to parent-of-origin by considering the two grandfathers' countries of birth. In a prospective cohort of 88,829 offspring, born in Jerusalem in 1964-76 we identified 637 cases through Israel's psychiatric registry. Relative risks (RR) were estimated for paternal and maternal grandfathers' countries of birth using proportional hazards methods, controlling for parents' ages, low social class and duration of marriage. After adjusting for multiple observations, we found no significant differences between descendants of maternal or paternal grandfathers born in Iraq, Iran, Turkey, Syria, Yemen, Morocco, Algeria, Tunisia, Libya/Egypt, Poland, USSR, Czechoslovakia, Germany or the USA. Those with paternal grandfathers from Romania (RR=1.9, 95% CI=1.3-2.8) or Hungary (1.6, 1.0-2.6) showed an increased incidence; however, those with maternal grandfathers from these countries experienced reduced incidence (RR=0.5, 0.3-0.8 and 0.4, 0.2-0.8). In post-hoc analyses we found that results were similar whether the comparison groups were restricted to descendants of other Europeans or included those from Western Asia and North Africa; and effects of paternal grandfathers from Romania/Hungary were more pronounced in females, while effects of maternal grandfathers from these countries were similar in males and females. These post-hoc 'hypothesis-generating' findings lead one to question whether some families with ancestors in Romania or Hungary might carry a variant or mutation at a parentally imprinted locus that is altering susceptibility to schizophrenia. Such a locus, if it exists, might involve the X chromosome

Objective: Increased incidence of schizophrenia is observed among some immigrant groups in Europe, with the offspring of immigrants, ie 'second-generation' immigrants particularly vulnerable. Few contemporary studies have evaluated the risk of schizophrenia among second-generation immigrants in other parts of the world. Methods: We studied the incidence of schizophrenia in relation to parental immigrant status in a population-based cohort of 88 829 offspring born in Jerusalem in 1964-1976. Parental countries of birth were obtained from birth certificates and grouped together as (1) Israel, (2) Other West Asia, (3) North Africa, and (4) Europe and industrialized countries. Cox proportional hazards methods were used in adjusting for sex, parents' ages, maternal education, social class, and birth order. Results: Linkage with Israel's Psychiatric Registry identified 637 people admitted to psychiatric care facilities with schizophrenia-related diagnoses, before 1998. Incidence of schizophrenia was not increased among second-generation immigrants in this birth cohort, neither overall nor by specific group. Conclusions: The difference in risk of schizophrenia among second-generation immigrants in Europe and in this Israeli birth cohort suggests that the nature of the immigration experience may be relevant to risk, including reasons for migration, the nature of entry, and subsequent position in the host country for immigrants and their offspring. Minority status may be of importance as, in later studies, immigrants to Israel from Ethiopia had increased risk of schizophrenia

Although it is known that schizophrenia is associated with social class, controversy exists as to the nature of this association. The authors studied the incidence of schizophrenia in relation to social class at birth in a population-based cohort of 88,829 offspring born in Jerusalem in 1964-1976. They constructed a six-point scale to index social class, based on paternal occupation at the time of birth, with each of 108 occupations being ranked by mean education. Cox proportional hazards methods were used in adjusting for sex, parents' ages, duration of marriage and birth order. Linkage with Israel's Psychiatric Registry identified 637 people admitted to psychiatric care facilities with schizophrenia-related diagnoses, before 1998. There was no gradient of risk for schizophrenia associated with social class at birth; however, offspring of fathers in the lowest social class showed a modest increase in risk (adjusted Relative Risk = 1.4; 95% Confidence interval = 1.1-1.8, P = 0.002). These data suggest that in contrast to many other health outcomes, there is not a continuous gradient for increasing schizophrenia with decreasing social class of origin. Instead, a modest increase in risk for schizophrenia was observed only for those born at the bottom of the social ladder

Uncertainty continues as to whether treatments for ovulation induction are associated with increased risk of cancer. The authors conducted a long-term population-based historical cohort study of parous women. A total of 15,030 women in the Jerusalem Perinatal Study who gave birth in 1974-1976 participated in a postpartum survey. Cancer incidence through 2004 was analyzed using Cox's proportional hazards models, controlling for age and other covariates. Women who used drugs to induce ovulation (n = 567) had increased risks of cancer at any site (multivariate hazard ratio (HR) = 1.36, 95% confidence interval (CI): 1.06, 1.74). An increased risk of uterine cancer was found among women treated with ovulation-inducing agents (HR = 3.39, 95% CI: 1.28, 8.97), specifically clomiphene (HR = 4.56, 95% CI: 1.56, 13.34). No association was noted between use of ovulation-inducing agents and ovarian cancer (age-adjusted HR = 0.61, 95% CI: 0.08, 4.42). Ovulation induction was associated with a borderline-significant increased risk of breast cancer (multivariate HR = 1.42, 95% CI: 0.99, 2.05). Increased risks were also observed for malignant melanoma and non-Hodgkin lymphoma. These associations appeared stronger among women who waited more than 1 year to conceive. Additional follow-up studies assessing these associations by drug type, dosage, and duration are needed.

PURPOSE: To explore the association between birth weight in offspring, a marker of the intrauterine environment, and mortality in their mothers, taking into account maternal pre-pregnancy characteristics, including maternal body mass index (BMI), smoking, and socioeconomic status. Distinguishing the effects of offspring's birth weight and pre-pregnancy characteristics on maternal outcome may provide clues regarding mechanisms underlying the association between birth weight and maternal mortality. METHODS: We studied long-term total mortality (average follow-up period, 29.1 years) in a population-based cohort of 13,185 mothers, aged 15 to 48 years at their offspring's birth, who delivered in West Jerusalem during 1974 through 1976. RESULTS: Univariate and multivariate Cox-proportional hazard models used to estimate the hazard of overall mortality among mothers indicated a nonlinear relationship with birth weight of offspring when introduced into the models as a continuous variable, and a linear positive association with maternal pre-pregnancy BMI. Inclusion of maternal BMI and other pre-pregnancy characteristics in the model did not alter the association between offspring's birth weight and mothers' all-cause mortality. When birth weight was introduced as a categorical variable, higher mortality was observed among mothers who gave birth to babies with birth weight less than 2500 g (hazard ratio [HR] = 1.90; 95% confidence interval [95%CI], 1.23-2.94) as compared to mothers whose offspring had birth weight between 3000 and 3499 g. The HR for mothers who gave birth to babies with birth weight 4000 g or more was 1.30 (95%CI, 0.88-1.91). CONCLUSIONS: Independent of pre-pregnancy maternal BMI and other characteristics, birth weight of offspring was associated with mortality in their mothers, suggesting that intrauterine metabolic events reflected by birth weight and not explained by maternal obesity, smoking, and socioeconomic status have remote consequences for maternal health. These findings underline the need to explore specific genetic and/or environmental mechanisms that account for these associations

OBJECTIVE: The purpose of this study was to examine the association between preeclampsia and cancer incidence. STUDY DESIGN: The Jerusalem Perinatal Study is a population-based cohort of all births to 41,206 residents of Western Jerusalem from 1964-76. Cancer incidence to 2004 was assessed by linkage of the cohort with the Israel Cancer Registry. Cox's proportional hazards models were constructed to estimate the hazard ratio for cancer among women who had had preeclampsia. RESULTS: Preeclampsia was associated with a 1.23-fold increased risk of cancer at all sites, a 37% increased risk of breast cancer, and more than a doubling of ovarian cancer risk. Analysis by morphologic condition yielded significantly increased risks for malignancies that were classed as cystic mucinous and serous (relative risk, 1.96; 95% CI, 1.00-3.83) and for ductal, lobular, and medullary carcinomas (relative risk, 1.40; 95% CI, 1.07-1.83). No differential association was observed by sex of offspring. CONCLUSION: Our study suggests that the previously described protective effect of preeclampsia on cancer is not universal

OBJECTIVE: To investigate whether incidence of twin deliveries is related to father's age, independently of mother's age, and whether it differs for same-sex or opposite-sex twin sets. STUDY DESIGN: In a program of research on effects of paternal age, this study used data from a prospective cohort of 92,408 offspring born in Jerusalem from 1964 to 1976. Of the 91,253 deliveries in the Jerusalem Perinatal Study, 1115 were twin deliveries. The data were analyzed with General Estimate Equations to inform unconditional logistic regression. RESULTS: After controlling for maternal age, odds ratios (ORs) and 95% confidence intervals (95% CI) associated with father's ages 25-34 and 35+ were 1.3 (1.1, 1.7) and 1.5 (1.2, 2.1) respectively, compared with fathers <25 years old. The effect of maternal age was partly explained by paternal age. The ORs for opposite-sex twin sets and male-male twin sets increased slightly with paternal age, while the OR for same-sex and female-female twin decreased. CONCLUSION: Studies of twins are used to estimate effects of genes and environment in a variety of diseases. Our findings highlight the need to consider paternal as well as maternal age when analyzing data on twins to explore etiology of diseases