To investigate whether advanced maternal age is associated with preterm birth, irrespective of parity.
Population-based registry study.
Swedish Medical Birth Register.
First, second, and third live singleton births to women aged 20 years or older in Sweden, from 1990 to 2011 (n = 2 009 068).
Logistic regression analysis was used in each parity group to estimate risks of very and moderately preterm births to women at 20-24, 25-29, 30-34, 35-39, and 40 years or older, using 25-29 years as the reference group. Odds ratios (ORs) were adjusted for year of birth, education, country of birth, smoking, body mass index, and history of preterm birth. Age-related risks of spontaneous and medically indicated preterm births were also investigated.
Very preterm (22-31 weeks of gestation) and moderately preterm (32-36 weeks) births.
Risks of very preterm birth increased with maternal age, irrespective of parity: adjusted ORs in first, second, and third births ranged from 1.18 to 1.28 at 30-34 years, from 1.59 to 1.70 at 35-39 years, and from 1.97 to 2.40 at =40 years. In moderately preterm births, age-related associations were weaker, but were statistically significant from 35-39 years in all parity groups. Advanced maternal age increased the risks of both spontaneous and medically indicated preterm births.
Advanced maternal age is associated with an increased risk of preterm birth, irrespective of parity, especially very preterm birth. Women aged 35 years and older, expecting their first, second, or third births, should be regarded as a risk group for very preterm birth.
Women aged 35 years and older should be regarded as a risk group for very preterm birth, irrespective of parity.
The aims of the present study were to evaluate the contribution of the genetic and environmental factors to the risk of teenage childbearing, and to study whether life style, socio-economic conditions, and personality traits could explain possible familial effects. We linked two population-based registers: the Swedish Twin Register and the Swedish Medical Birth Register. The study covers female twin pairs born between 1953 and 1958, having their first infant before the age of 30 years (n = 1885). In order to separate familial effects from other environmental influences, and genetic effects from shared environmental effects, only complete twin pairs with known zygosity were included, in all 260 monozygotic and 370 dizygotic twin pairs. We used quantitative genetic analyses to evaluate the importance of genetic and environmental effects for liability to teenage childbearing. Logistic regression analyses were used to estimate the effects of life style, socio-economic situation, and personality on the probability of teenage childbearing, and to study whether psychosocial factors could explain possible familial effects. Fifty-nine percent (0-76%) of the variance in being a teenage mother was attributable to heritable factors; 0% (0-49%) was due to shared environmental factors; and 41% (23-67%) was explained by non-shared environmental factors. Thus, the data were consistent with the hypothesis that the familial aggregation of teenage childbearing is completely explained by genetic factors, although the alternative hypothesis that familial aggregation is entirely explained by shared environmental factors cannot be ruled out. Significant effects of smoking habits, housing conditions, and educational level were found in relation to liability to teenage childbearing. However, the familial effects on risk of teenage childbearing were not mediated through similarities in life style and socio-economic factors. When studying risk factors for teenage childbearing, it is recommended to include life style and socio-economic variables as well as information about family history of teenage childbearing. Twin Research (2000) 3, 23-27.
In a previous prospective study, we outlined a screening programme aiming at detection of a high-risk group for small-for-gestational-age (SGA) pregnancies. The present study evaluates this screening programme in all women delivering at the hospital in 1 year and in all women delivering SGA infants during a 6-year period. When screening for SGA, using symphysis-fundus measurements together with risk factors, the false positive rates were unacceptably high. When only using repeated measurements of the symphysis-fundus distance the results were more acceptable (sensitivity 59%, specificity 97%, positive predictive value 15%). Between 1980 to 1985, 18,604 live singleton infants were born. Altogether 156 infants were assessed as SGA (birthweight for gestational age less than -2 S.D.). Two antenatal records from SGA pregnancies were missing and in 14 pregnancies, antenatal detection of SGA would not have improved the prognosis of the infants (severe congenital malformations or preterm delivery due to maternal diseases). Thus, of 140 SGA pregnancies in focus pathological symphysis-fundus measurements occurred in 63%. It is concluded that by repeated measurements of the symphysis-fundus distance, it is quite possible to form a high-risk group for SGA. In this high-risk group, including less than 4% of the pregnant population, the majority of SGA pregnancies are found.
To examine the associations of maternal and infant complications with postpartum hospitalisation for psychosis in women with a pre-conception history of psychiatric hospitalisation.
Swedish medical birth register.
Primiparous women who gave birth between 1 January 1987 and 31 December 2001, and who had a pre-conception history of psychiatric hospitalisation but who were not hospitalised during pregnancy (n = 1842).
International Classification of Diseases (ICD) codes were used to identify prenatal, obstetric, postpartum maternal complications, and newborn health conditions. We used multivariable logistic regression to describe the associations between maternal and infant health conditions and the odds for postpartum hospitalisation for psychosis.
Psychiatric hospitalisation within 90 days of delivery.
Compared with women who did not have a postpartum psychiatric hospitalisation, hospitalised women were at 2.3 times higher odds (95% CI 1.0-4.9) of having non-psychiatric puerperium complications (e.g. infection, lactation problems or venous complications). No other maternal complications were associated with postpartum psychiatric hospitalisation. Although their infants were at no higher odds for health complications, the offspring of women who had a postpartum psychiatric hospitalisation were at 4.1 times higher odds (95% CI 1.3-12.6) of death within the first 365 days of life than those of women who were not hospitalised.
We found no prenatal indicators of postpartum risk for psychiatric hospitalisation among high-risk women, but they had higher odds of postpartum pregnancy-related medical problems and, rarely, offspring death.
Cites: Arch Gen Psychiatry. 2007 Jan;64(1):42-817199053
Cites: J Womens Health (Larchmt). 2006 May;15(4):352-6816724884
Cites: PLoS Med. 2009 Feb 10;6(2):e1319209952
Cites: Am J Psychiatry. 2009 Apr;166(4):405-819339365
AIM: To study the effect of size at birth on different dimensions of intellectual capacity. METHODS: The study comprised a population-based cohort including all male single births without congenital malformations in Sweden from 1973 to 1976, and conscripted before 1994 (n = 168 068). Information from the Swedish Birth Register was individually linked to the Swedish Conscript Register. The test of intellectual performance included four different dimensions: logical, spatial, theoretical and verbal capacity. These data were available for 80-86% of the males at conscription. RESULTS: Compared with boys born appropriate for gestational age, males born small for gestational age (SGA) had an increased risk for subnormal performance in all four dimensions. Among males born SGA who were also of short adult stature at conscription, and in individuals born SGA with a head circumference
OBJECTIVE: Intrauterine nutrition approximated by birth weight has been shown to be inversely associated with risk of coronary heart disease (CHD). By investigating the association within twin pairs discordant for disease, the influence of genetic and early environmental factors is substantially reduced. METHODS: We have investigated the association between birth weight and angina pectoris in same-sexed twins with known zygosity included in the population-based Swedish Twin Registry. Self-reports of birth weight and angina pectoris were collected in a telephone interview between 1998 and 2000. The cohort analyses were based on 4594 same-sexed twins, and the within-pair analyses included 55 dizygotic and 37 monozygotic twin pairs discordant for angina pectoris. Odds ratios (OR) and 95% confidence intervals (CI) were calculated by logistic regression. RESULTS: Compared with birth weight between 2.0 and 2.9 kg, low birth weight (
Does the intergenerational influence on birthweight and birth length remain within female dizygotic and monozygotic twin pairs?
The intergenerational influence on birthweight and birth length remained within dizygotic but not within monozygotic twin pairs.
Low birthweight is associated with increased morbidity and mortality in both the short and long term; therefore it is important to understand determinants of fetal growth. There is a known intergenerational association between parents' and offspring's size at birth.
This is a register-based cohort study with a nested within-twin-pair comparison. The study is retrospective, but based on prospectively collected information. The study population included 8685 monozygotic and like-sexed dizygotic female twins born in Sweden from 1926 to 1985, who had given birth to their first infant between 1973 and 2009.
This study is set in Sweden and used data from the Swedish Twin Register and the Swedish Medical Birth Register. We used generalized estimating equations to obtain regression coefficients with 95% confidence intervals (CI) for the outcomes: offspring birthweight and birth length. To control for genetic and shared environmental factors, we performed within-twin-pair analyses in 1479 dizygotic and 1526 monozygotic twin pairs.
In the cohort of both dizygotic and monozygotic twins, there was an association between mother's and offspring's size at birth. Within-dizygotic twin pairs, a 500-g increase from the twin pair's mean birthweight was associated with increased offspring birthweight [70 g (95% CI: 35-106)] and birth length [0.22 cm (95% CI: 0.07-0.38)]. The corresponding increase in birth length of 1 cm was estimated to increase offspring's birthweight by 26 g (95% CI: 12-40) and birth length by 0.11 cm (95% CI: 0.04-0.17). Within-monozygotic twin pairs there were no such associations.
This study is limited to twins who themselves or whose co-twin voluntarily responded to questionnaires.
The intergenerational influence on size at birth is suggested to be due to direct or indirect genetic factors.
BACKGROUND: Epidemiological studies that used birthweight as a crude marker of fetal growth have suggested that low birthweight is associated with increased risk of coronary heart disease. Through investigation of this association within same-sexed twin pairs, confounding by genetic and early environmental factors can be greatly decreased. We undertook a case-control study in twins discordant for acute myocardial infarction (AMI). METHODS: The case-control study was nested within the population-based Swedish Twin Registry and linked with the national cause-of-death and hospital-discharge registries. We manually retrieved birth records containing information on birth and maternal characteristics for 132 same-sexed twin pairs discordant for AMI and 118 individually matched control twin pairs. FINDINGS: In comparisons between AMI cases and external matched control twins, cases had significantly lower birthweight (mean 2556 [SD 500] vs 2699  g, p=0.04), birth length (47.1 [2.8] vs 47.9 [2.7] cm, p=0.04), and head circumference (33.0 [1.8] vs 33.5 [2.0] cm, p=0.03) than controls. In within-pair comparisons between AMI cases and healthy co-twins, no significant differences in birth measurements were found (birthweight 2458  vs 2534  g, p=0.73; birth length 47.1 [2.8] vs 47.2 [2.8] cm, p=0.91; head circumference 33.0 [1.7] vs 33.0 [1.8] cm, p=0.92). INTERPRETATION: The lack of an association between birth characteristics and AMI within twin pairs suggests that previously reported associations may be influenced by genetic and early environmental factors, or possibly, by unmeasured maternal factors that operate independently of birthweight.
Comment In: Lancet. 2001 Jun 23;357(9273):1990-111438125
BACKGROUND: Some epidemiologic studies have suggested that the ingestion of caffeine increases the risk of spontaneous abortion, but the results have been inconsistent. METHODS: We performed a population-based, case-control study of early spontaneous abortion in Uppsala County, Sweden. The subjects were 562 women who had spontaneous abortion at 6 to 12 completed weeks of gestation (the case patients) and 953 women who did not have spontaneous abortion and were matched to the case patients according to the week of gestation (controls). Information on the ingestion of caffeine was obtained from in-person interviews. Plasma cotinine was measured as an indicator of cigarette smoking, and fetal karyotypes were determined from tissue samples. Multivariate analysis was used to estimate the relative risks associated with caffeine ingestion after adjustment for smoking and symptoms of pregnancy such as nausea, vomiting, and tiredness. RESULTS: Among nonsmokers, more spontaneous abortions occurred in women who ingested at least 100 mg of caffeine per day than in women who ingested less than 100 mg per day, with the increase in risk related to the amount ingested (100 to 299 mg per day: odds ratio, 1.3; 95 percent confidence interval, 0.9 to 1.8; 300 to 499 mg per day: odds ratio, 1.4; 95 percent confidence interval, 0.9 to 2.0; and 500 mg or more per day: odds ratio, 2.2; 95 percent confidence interval, 1.3 to 3.8). Among smokers, caffeine ingestion was not associated with an excess risk of spontaneous abortion. When the analyses were stratified according to the results of karyotyping, the ingestion of moderate or high levels of caffeine was found to be associated with an excess risk of spontaneous abortion when the fetus had a normal or unknown karyotype but not when the fetal karyotype was abnormal. CONCLUSIONS: The ingestion of caffeine may increase the risk of an early spontaneous abortion among non-smoking women carrying fetuses with normal karyotypes.