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Allen J Wilcox

Publications and source records attributed to Allen J Wilcox.

At least 19 recordsLinked to original sources
PubMed2005

Recurrence of pre-eclampsia across generations: exploring fetal and maternal genetic components in a population based cohort.

OBJECTIVES: To assess the impact on risk of pre-eclampsia of genes that work through the mother, and genes of paternal origin that work through the fetus. DESIGN: Population based cohort study. SETTING: Registry data from Norway. PARTICIPANTS: Linked generational data from the medical birth registry of Norway (1967-2003): 438,597 mother-offspring units and 286,945 father-offspring units. MAIN OUTCOME MEASURES: Pre-eclampsia in the second generation. RESULTS: The daughters of women who had pre-eclampsia during pregnancy had more than twice the risk of pre-eclampsia themselves (odds ratio 2.2, 95% confidence interval 2.0 to 2.4) compared with other women. Men born after a pregnancy complicated by pre-eclampsia had a moderately increased risk of fathering a pre-eclamptic pregnancy (1.5, 1.3 to 1.7). Sisters of affected men or women, who were themselves born after pregnancies not complicated by pre-eclampsia, also had an increased risk (2.0, 1.7 to 2.3). Women and men born after pre-eclamptic pregnancies were more likely to trigger severe pre-eclampsia in their own (or their partner's) pregnancy (3.0, 2.4 to 3.7, for mothers and 1.9, 1.4 to 2.5, for fathers). CONCLUSIONS: Maternal genes and fetal genes from either the mother or father may trigger pre-eclampsia. The maternal association is stronger than the fetal association. The familial association predicts more severe pre-eclampsia.

Birth Order↗
PubMed2005

Cleft lip and palate versus cleft lip only: are they distinct defects?

Cleft lip defects are usually regarded as a single entity, with the assumption that an accompanying cleft palate represents the more severe form. The authors linked data from the Medical Birth Registry of Norway with medical records from two centralized centers to provide a population-based data set. They assessed the distribution of cleft lip only and cleft lip with cleft palate by covariate. Among 1.8 million Norwegian livebirths between 1967 and 1998, there were 1,572 cases of cleft lip with cleft palate and 1,122 cases with cleft lip only. Seventeen percent of those with cleft lip and palate had another defect compared with 9% of those with cleft lip only. For boys, the risk was greater for cleft lip and palate than for cleft lip only (odds ratio=2.4 vs. 1.8, p<0.001 for difference). The risk of cleft lip only, but not of cleft lip and palate, was increased for twins (odds ratio=1.6 vs. 1.1, p=0.11) and infants whose parents were first cousins (odds ratio=2.7 vs. 0.7, p=0.07). Although cleft lip with cleft palate may simply represent a more severe form of the defect, epidemiologic assessments of cleft lip should, when possible, include separate analyses of these two groups.

Abnormalities, Multiple↗
PubMed2005

Intact HCG, free HCG beta subunit and HCG beta core fragment: longitudinal patterns in urine during early pregnancy.

BACKGROUND: Detecting and monitoring early pregnancy depend on the measurement of HCG. Little is known about how production of various forms of HCG may evolve over the earliest weeks of pregnancy, particularly in naturally conceived pregnancies. METHODS: We describe the daily excretion of three urinary HCG analytes during the first 6 weeks post-conception in 37 naturally conceived pregnancies ending in singleton birth. We assayed daily first morning urine samples for intact HCG, free beta subunit and beta?core fragment, plus the combined measurement of these HCG forms. We calculated doubling times for each analyte and the inter- and intra-subject day-to-day variation. RESULTS: Intact HCG and the free beta subunit were initially the predominant forms of HCG, with the beta core fragment emerging as the predominant form in the fifth week after conception. Intact HCG and the free beta subunit showed the most day-to-day variability, and were transiently undetectable even 10 days after detection of pregnancy. The most stable estimate of doubling time was provided by the combined measurement of all these forms. CONCLUSIONS: Although intact HCG is usually regarded as the main analyte for detection and monitoring of early pregnancy, it can fluctuate markedly during early pregnancy. This variability could affect pregnancy test results based on early pregnancy urine, and may distort estimates of doubling time. Assays that combine several forms of HCG may be more reliable.

Adult↗
PubMed2005

Has human fertility declined over time?: why we may never know.

BACKGROUND: Reports of decreased semen quality over time have raised concerns about possible reductions in human fertility. Studies of couple fertility have produced conflicting results. We evaluate how changes in the availability and use of effective contraception and induced abortion might bias the direct study of time trends in couple fertility. METHODS: We assess the potential for bias in the context of 2 common study designs: (1) a study of time-to-pregnancy that estimates fecundability (excluding unintended pregnancies) and (2) a study of infertility rates that categorizes couples as fertile or infertile (including couples with unintended pregnancies as fertile). RESULTS: In time-to-pregnancy studies, bias alone could produce more than a 2-fold apparent increase in fecundability over recent decades. In studies of infertility rates, the bias works in the opposite direction: a 30% underestimation of infertility during earlier decades could produce an apparent decrease in fertility over time. CONCLUSIONS: Over the past 5 decades, changes in social factors that affect the rate and fate of unintended pregnancies could substantially bias time trends in fertility. These biases may explain the conflicting reports in the literature. Except in rare settings in which the factors affecting reproductive choices have not changed, it is probably impossible to identify biologic changes in fertility over recent decades.

Abortion, Induced↗
PubMed2005

Terms in reproductive and perinatal epidemiology: 2. Perinatal terms.

This is the second of a two part glossary of terms used in reproductive and perinatal epidemiology. The purpose is to provide a reference for terms that are widely (if not always consistently) used in this field. While a glossary cannot resolve all these problems, it provides a point of reference for understanding them. Part 1 covered terms relevant mostly to events and conditions before birth. Part 2 emphasises terms used during the time around and after birth.

Perinatology↗
PubMed2004

Height and risk of severe pre-eclampsia. A study within the Danish National Birth Cohort.

BACKGROUND: Pre-eclampsia shares a number of risk factors with cardiovascular disease (CVD). Women with recurrent pre-eclampsia or pre-eclampsia early in pregnancy reportedly have an increased long-term risk of CVD. Short stature is a risk factor for CVD but has rarely been examined in relation to pre-eclampsia. METHODS: We used data from 59 968 singleton live births in the Danish National Birth Cohort born between 1998 and 2001 to assess risk of severe pre-eclampsia/eclampsia (296 cases) in relation to self-reported height. We examined the association in multiple logistic regressions stratified by parity. RESULTS: Among primiparas there was a weak association (compared with women <165 cm, women >172 cm had on OR of 0.79, 95% CI: 0.55, 1.14). Among multiparas, the tallest women had an adjusted OR of 0.42 (95% CI: 0.20, 0.87) of developing severe pre-eclampsia compared with women <165 cm. The OR per centimetre was 0.94 (95% CI: 0.91, 0.97). Self-reported pre-existing hypertension did not explain this association, which also persisted when the analysis was restricted to non-overweight women. CONCLUSIONS: Short stature was associated with a higher risk of severe pre-eclampsia in multiparas participating in the Danish National Birth Cohort.

Body Height↗
PubMed2004

Incidence of spontaneous abortion among pregnancies produced by assisted reproductive technology.

BACKGROUND: There has been increasing number of pregnancies following assisted reproductive technology treatment and their survival is understandably a matter of interest. The relative risk of spontaneous abortion in these pregnancies remains unclear. The objectives of this study were to quantify the relative risk in assisted reproductive technology pregnancies in relation to two cohorts of naturally conceived pregnancies and to assess the possible risk factors for spontaneous abortion among assisted reproductive technology pregnancies. METHODS: Three cohorts of pregnancies, 1945 pregnancies conceived following assisted reproductive technology treatment in a tertiary infertility clinic, 549 natural pregnancies in a prospective study of lifestyle and pregnancy (the Ford cohort), and 4265 pregnancies from another cohort (the Treloar cohort), were used in the study. RESULTS: After adjusting for age, the relative risk of spontaneous abortion was 1.20 (95% CI 1.03-1.46) in the assisted reproductive technology cohort in comparison with the Ford cohort. Within the assisted reproductive technology cohort, a history of spontaneous abortion predicted increased risk, while a low level of ovarian stimulation seemed to be related to a reduced risk. CONCLUSIONS: The study showed that the risk of spontaneous abortion was slightly increased in the assisted reproductive technology pregnancies after adjusting for maternal age and previous spontaneous abortion. Within the assisted reproductive technology cohort, several variables, including the level of stimulation, appeared to be linked with the risk of spontaneous abortion.

Abortion, Spontaneous↗
PubMed2004

On precision.

Explore the source record for details and available documents.

Communication↗
PubMed2003

Exploring the effects of methylenetetrahydrofolate reductase gene variants C677T and A1298C on the risk of orofacial clefts in 261 Norwegian case-parent triads.

Folic acid and the methylenetetrahydrofolate reductase (MTHFR) gene have both been implicated in the etiology of orofacial clefts. The authors selected 261 case-parent triads (173 cases with cleft lip with or without cleft palate (CL/P) and 88 cases with cleft palate only (CPO)) from a Norwegian population-based study of orofacial clefts (May 1996-1998). A case-parent triad design was used to examine whether MTHFR variants C677T and A1298C, and their haplotypes, are risk factors for orofacial clefts. Among CL/P cases, the child's genotype at C677T or A1298C did not influence the risk. However, children of mothers carrying the C677T variant allele had a lower risk of CL/P. For CPO, children carrying the C677T variant allele had about a twofold increased risk, whereas the mother's genotypes did not contribute to the risk. The haplotype-based transmission/disequilibrium test showed that except for 677T/1298A (p = 0.06), none of the other haplotypes showed evidence of excess transmission to the offspring. The authors also explored interaction of C677T with maternal use of folic acid among children with CPO. Surprisingly, the risk associated with the child's carrying either CT or TT was higher (fourfold) when the mother used folic acid. These findings suggest a possible role of MTHFR and folic acid in the causation of orofacial clefts, but the strength and direction of these effects remain to be clarified.

Adolescent↗
PubMed2003

Subfecundity as a correlate of preeclampsia: a study within the Danish National Birth Cohort.

A long interpregnancy interval is associated with preeclampsia. If some women experiencing a long interval between births had difficulty conceiving, subfecundity and preeclampsia may share a common etiology. Therefore, the authors examined the association between subfecundity and preeclampsia. By using interview data collected during the second trimester of pregnancy (1998-2001) from women participating in the Danish National Birth Cohort, they identified 20,034 and 24,698 singleton livebirths to primiparous and multiparous women, respectively, for whom preeclampsia information was available from hospital birth records. Among women with no known hypertension, the authors estimated a higher risk of preeclampsia in those with longer times to pregnancy (TTPs), after adjustment for maternal age, prepregnancy body mass index, and smoking. Compared with primiparas who became pregnant right away (referent category), the risk of preeclampsia increased with TTP and then stabilized for women taking 6 months or longer to conceive, whose risk of preeclampsia increased by 50%. Multiparas also had an increased risk, but only those reporting a TTP longer than 12 months (odds ratio = 2.47, 95% confidence interval: 1.30, 4.69). The authors found that a long TTP was associated with preeclampsia, supporting the hypothesis that some factors delaying clinically recognized conception may also be in a causal pathway for preeclampsia.

Adult↗
PubMed2003

Variants of developmental genes (TGFA, TGFB3, and MSX1) and their associations with orofacial clefts: a case-parent triad analysis.

We selected 262 case-parent triads from a population-based study of orofacial clefts in Norway, and examined variants of developmental genes TGFA, TGFB3, and MSX1 in the etiology of orofacial clefts. One hundred seventy-four triads of cleft lip cases (CL+/-P) and 88 triads of cleft palate only cases (CPO) were analyzed. There was little evidence for an association of any of these genes with CL+/-P. The strongest association was a 1.7-fold risk with two copies of the TGFB3-CA variant (95% CI=0.9-3.0). Among CPO cases, there was a 3-fold risk with two copies of the TGFA TaqI A2 allele, and no increase with one copy. Assuming this to be a recessive effect, we estimated a 3.2-fold risk among babies homozygous for the variant (95% CI=1.1-9.2). Furthermore, there was strong evidence of gene-gene interaction. While there was only a weak association of the MSX1-CA variant with CPO, the risk was 9.7-fold (95% CI=2.9-32) among children homozygous for both the MSX1-CA A4 allele and the TGFA A2 allele. No association of CPO with the TGFA variant was seen among the other MSX1-CA genotypes. In conclusion, no strong associations were found between CL+/-P and variants at these three genes. There was a possible recessive effect of the TGFA TaqI variant on the risk of CPO, with a 3-fold risk among children homozygous for the variant. The effect of this TGFA genotype was even stronger among children homozygous for the MSX1-CA A4 allele, raising the possibility of interaction between these two genes.

Adult↗
PubMed2003

Cleft palate, transforming growth factor alpha gene variants, and maternal exposures: assessing gene-environment interactions in case-parent triads.

We have previously reported a threefold risk of cleft palate only (CPO) among children homozygous for the less common allele A2 at the TaqI marker site of the transforming growth factor alpha gene (TGFA) (Jugessur et al. [2003a] Genet. Epidemiol. 24:230-239). Here we assess possible interaction between the child's TGFA TaqI A2A2 genotype and maternal cigarette smoking, alcohol consumption, use of multivitamins and folic acid. This was done by comparing the strength of genetic associations between strata of exposed and unexposed case-parent triads. We also looked for possible gene-gene interaction with the polymorphic variant C677T of the folic acid-metabolizing gene MTHFR. We analyzed a total of 88 complete CPO triads selected from a population-based study of orofacial clefts in Norway (May 1996-1998). No evidence of interaction was observed with either smoking or alcohol use. The risk associated with two copies of the A2 allele at TGFA TaqI was strong among children whose mothers did not use folic acid (relative risk=4.5, 95% confidence interval=1.3-15.7), and was only marginal among children whose mothers reported using folic acid (RR=1.4, 95% CI=0.2-12.7). Although the interaction between the child's genotypes at TGFA TaqI and MTHFR-C677T was not statistically significant, the effect of the TGFA TaqI A2A2 genotype appeared to be stronger among children with either one or two copies of the T-allele at C677T (RR=4.0, 95% CI=1.1-13.9) compared to children homozygous for the C-allele (RR=1.7, 95% CI=0.2-15.7). In conclusion, we find little evidence of interaction between the child's genotypes at TGFA TaqI and various exposures for cleft palate, with the possible exception of folic acid intake.

Adult↗
PubMed2003

Rescue of the corpus luteum in human pregnancy.

Rescue of the corpus luteum from its programmed senescence maintains progesterone production required for pregnancy. In primates, chorionic gonadotropin produced by the developing conceptus acts as the primary luteotrophic signal. The purpose of this research was to assess corpus luteum rescue by examining changes in daily urinary progesterone metabolite levels during the first week after implantation. We determined the variability in progesterone metabolite profiles and evaluated its relationship to early pregnancy loss in 120 naturally conceived human pregnancies, including 43 early pregnancy losses. In other primates, an abrupt increase in the progesterone metabolite occurs at the time of implantation. This pattern occurred in an estimated 45% of the pregnancies in the present study. In the remaining pregnancies, there was a delayed rise (18%), neither a rise or decline (22%), or a decline (15%) during the week after implantation. The estimated rate of early pregnancy loss increased across these categories (from 5% loss with an abrupt rise at implantation to 100% loss with progesterone metabolite decline). Low urinary hCG levels in early pregnancy were significant determinants of a decline in postimplantation progesterone metabolite. However, preimplantation steroid metabolite levels were not significant, suggesting no inherent problem with the corpus luteum. Examination of individual progesterone metabolite profiles in relation to hCG profiles also indicated that few losses were caused by corpus luteum failure. Delineating the functional importance of an abrupt progesterone rise at the time of implantation may provide new strategies for promoting successful implantation in assisted reproduction.

Abortion, Spontaneous↗