Higher Rates Of Preterm Birth Research Articles

Depression, SSRI Use Tied to Higher Preterm Birth Rate

Depression, SSRI Use Tied to Higher Preterm Birth Rate

Birth outcomes in the Inuit-inhabited areas of Canada.

Information on health disparities between Aboriginal and non-Aboriginal populations is essential for developing public health programs aimed at reducing such disparities. The lack of data on disparities in birth outcomes between Inuit and non-Inuit populations in Canada prompted us to compare birth outcomes in Inuit-inhabited areas with those in the rest of the country and in other rural and northern areas of Canada. We conducted a cohort study of all births in Canada during 1990-2000 using linked vital data. We identified 13,642 births to residents of Inuit-inhabited areas and 4,054,489 births to residents of all other areas. The primary outcome measures were preterm birth, stillbirth and infant death. Compared with the rest of Canada, Inuit-inhabited areas had substantially higher rates of preterm birth (risk ratio [RR] 1.45, 95% confidence interval [CI] 1.38-1.52), stillbirth (RR 1.68, 95% CI 1.38-2.04) and infant death (RR 3.61, 95% CI 3.17-4.12). The risk ratios and absolute differences in risk for these outcomes changed little over time. Excess mortality was observed for all major causes of infant death, including congenital anomalies (RR 1.64), immaturity-related conditions (RR 2.96), asphyxia (RR 2.43), sudden infant death syndrome (RR 7.15), infection (RR 8.32) and external causes (RR 7.30). Maternal characteristics accounted for only a small part of the risk disparities. Substantial risk ratios for preterm birth, stillbirth and infant death remained when the comparisons were restricted to other rural or northern areas of Canada. The Inuit-inhabited areas had much higher rates of preterm birth, stillbirth and infant death compared with the rest of Canada and with other rural and northern areas. There is an urgent need for more effective interventions to improve maternal and infant health in Inuit-inhabited areas.

Birth outcomes and pregnancy complications of women with uterine leiomyoma—a population-based case-control study

Objective Uterine leiomyoma is not a rare pathological condition in pregnant women; thus the aim of the study was to evaluate the recent progress in the treatment of these pregnant women on the basis of the association of leiomyoma in pregnancy (LP) with pregnancy complications and birth outcomes including structural birth defects, i.e. congenital abnormalities (CA) in the offspring. Design Cases with CA and matched controls without CA in the population-based Hungarian Case-Control Surveillan- ce System of Congenital Abnormalities (HCC SCA) were evaluated. Only women with prospectively and medically recorded LP in prenatal maternity logbook and medically recorded birth outcomes (gestational age, birth weight, CA) were included to the study. Setting the HCCSCA, 1980-1996 contained 22,843 cases with CA and 38,151 matched controls without CA. Population Hungarian pregnant women and their informative offspring: live births, stillbirths and prenatally diagnosed malformed fetuses. Methods Comparison of birth outcomes of ca- ses with matched controls and pregnancy com- plications of pregnant women with or without LP. Main outcome measures Pregnancy complications, mean gestational age at delivery and birth weight, rate of preterm birth, low birthweight, CA. Results A total of 34 (0.15%) cases had mothers with LP compared to 71 (0.19%) controls. There was a higher incidence of threatened abortion, placental disorders, mainly abruption placentae and anaemia in mothers with LP. There was no significantly higher rate of preterm birth in the newborns of women with LP but their mean birth weight was higher and it associated with a higher rate of large birthweight newborns. A higher risk of total CA was not found in cases born to mothers with LP (adjusted OR with 95% CI = 0.7, 0.5-1.1), the spe- cified groups of CAs were also assessed versus controls, but a higher occurrence of women with LP was not revealed in any CA group. Con- clusions Women with LP have a higher risk of threatened abortion, placental disorders and anaemia, but a higher rate of adverse birth outcomes including CAs was not found in their offspring.

The worldwide incidence of preterm birth: a systematic review of maternal mortality and morbidity

To analyse preterm birth rates worldwide to assess the incidence of this public health problem, map the regional distribution of preterm births and gain insight into existing assessment strategies. Data on preterm birth rates worldwide were extracted during a previous systematic review of published and unpublished data on maternal mortality and morbidity reported between 1997 and 2002. Those data were supplemented through a complementary search covering the period 2003-2007. Region-specific multiple regression models were used to estimate the preterm birth rates for countries with no data. We estimated that in 2005, 12.9 million births, or 9.6% of all births worldwide, were preterm. Approximately 11 million (85%) of these preterm births were concentrated in Africa and Asia, while about 0.5 million occurred in each of Europe and North America (excluding Mexico) and 0.9 million in Latin America and the Caribbean. The highest rates of preterm birth were in Africa and North America (11.9% and 10.6% of all births, respectively), and the lowest were in Europe (6.2%). Preterm birth is an important perinatal health problem across the globe. Developing countries, especially those in Africa and southern Asia, incur the highest burden in terms of absolute numbers, although a high rate is also observed in North America. A better understanding of the causes of preterm birth and improved estimates of the incidence of preterm birth at the country level are needed to improve access to effective obstetric and neonatal care.

Association of Maternal Medical Conditions and Unfavorable Birth Outcomes: Findings from the 1996–2003 Mississippi Linked Birth and Death Data

This study aimed to identify factors contributing to high rates of preterm birth (PTB), low birth weight (LBW) and infant mortality in Mississippi while considering both traditional risk factors and maternal medical conditions. The retrospective cohort study used 1996-2003 Mississippi linked birth and infant death files. Multiple logistic regression was used to investigate association between maternal medical conditions and unfavorable birth outcomes. Along with traditional risk factors, hypertension was significantly associated with PTB and LBW. Women with hypertension were about 2.2 and 3.2 times as likely to have PTB and LBW, respectively. Hydramnios/oligohydramnios increased 1.8-4.4 folds of risk for PTB, LBW and infant death and was significantly associated with the unfavorable birth outcomes. Non-Hispanic black women were about 1.5-2.0 times as likely to have an unfavorable birth outcome compared to non-Hispanic white women. Maternal education and prenatal care effect appeared to be modified by maternal race. Certain maternal medical conditions may be contributing to PTB, LBW and infant mortality rates identifying preconception and prenatal healthcare as possible strategies for reducing unfavorable outcomes. Results suggest that different risk profiles for unfavorable outcomes may exist according to maternal race highlighting the need to consider racial groups separately when further exploring the sociodemographic and/or health-related factors that contribute to unfavorable birth outcomes.

OP29.06: Mid-second trimester abdominal circumference ratio in a twin gestation predicts poor perinatal outcome

The abdominal circumference (AC) ratio has been known to be a good predictor of birthweight discordance in twin pregnancy. The aim of this study was to evaluate the feasibility of the mid-second trimester AC ratio in predicting poor perinatal outcomes of twin gestations. The study population consisted of 150 consecutive twin pairs that were delivered between Jan 2004 and Jun 2007. Pregnancies complicated by intrauterine death or congenital anomaly were excluded. AC ratios were measured between 19–25 weeks' gestation. Birth weight discordance was defined as ≥ 25% difference in birth weight, relative to the larger twin. Receiver operating curve analysis was used to select a cut-off of the AC ratio for prediction of birthweight discordance. Perinatal outcome was compared between patients with a decreased AC ratio (an increased AC difference) and those with a normal AC ratio. 1) Mid-second trimester prediction of birth weight discordance in a twin pair, using an AC ratio with a cut off of 0.91, had a sensitivity of 67%, specificity of 89%, positive predictive value of 50% and negative predictive value of 94%. 2) Women with an AC ratio < 0.91 had a significantly higher rate of preterm birth < 34 weeks' gestation, birthweight discordance, small for gestational age (SGA) of one or both neonates in a pair than did those with an AC ratio ≥ 0.91 (preterm birth < 34 weeks of gestation: 32% vs 12%, P < .05; birth weight discordance: 50% vs 6%, P < .001; SGA: 31% vs 12%, P < .05). 3) Neonates with an AC ratio < 0.91 had a significantly higher rates of mechanical ventilator use, duration of NICU care > 30 days and neonatal death than those with an AC ratio ≥ 0.91 (mechanical ventilator use: 28% vs 13%, P < .05; duration of NICU care > 30 days: 18% vs 6%, P < .01; neonatal death: 13% vs 3%, P < .01). Abdominal circumference ratio < 0.91 in mid-second trimester was a good predictor of poor perinatal outcome in twin gestations.

18th Communication: Preterm Birth Rates and Maternal Occupation – The Importance of Age and Number of Live Births As Confounding Factors

BACKGROUND AND AIM: Socio-economic status, as described by maternal occupation, is an important determinant of the rate of preterm births, as are age and parity. We aimed to investigate the influence on preterm birth rates of maternal occupation, age and number of live births, and the interaction of these factors. MATERIAL AND METHODS: We analysed data of 2 130 584 singleton pregnancies from the German perinatal statistics of 1995-2000. Preterm birth rates, stratified according to age and number of live births, were calculated for the total population and for two (of seven) categories of maternal occupation coded for in German perinatal statistics, “unskilled labourers” and “highly qualified employees and entrepreneurs”. Differences between preterm birth rates of women in these two occupational categories were calculated and standardised according to age and number of live births. RESULTS: Overall rates of preterm birth were 7 % (total population), 7.8 % (unskilled labourers), and 6.3 % (highly qualified employees and entrepreneurs). Age and number of live births both exhibited a U-shaped influence on preterm delivery rates. Rates were lowest for women aged 25-29 (higher for younger and older women) and those giving birth to their second child (higher for primiparae and those with ≥ 3 live births). While the crude overall difference in preterm birth rates between the two occupational groups was only 1.5 %, the overall difference standardised according to age and number of live births was 2.3 %. Taking age and number of live births into account, the differences between preterm birth rates in certain subgroups can substantially exceed the overall difference between occupational categories. In women ≥ 40 with ≥ 4 live births, unskilled labourers have an 8.2 % higher rate of preterm births (13.8 vs. 5.6 %). CONCLUSIONS: When analysing the influence of maternal socio-economic status (occupation) on preterm birth rates it is important to take account of confounding factors such as age and number of live births. The rates of preterm delivery presented here may serve as an aid in counselling women on the risk of preterm birth.

Perinatal outcomes in a South Asian setting with high rates of low birth weight.

BackgroundIt is unclear whether the high rates of low birth weight in South Asia are due to poor fetal growth or short pregnancy duration. Also, it is not known whether the traditional focus on preventing low birth weight has been successful. We addressed these and related issues by studying births in Kaniyambadi, South India, with births from Nova Scotia, Canada serving as a reference.MethodsPopulation-based data for 1986 to 2005 were obtained from the birth database of the Community Health and Development program in Kaniyambadi and from the Nova Scotia Atlee Perinatal Database. Menstrual dates were used to obtain comparable information on gestational age. Small-for-gestational age (SGA) live births were identified using both a recent Canadian and an older Indian fetal growth standard.ResultsThe low birth weight and preterm birth rates were 17.0% versus 5.5% and 12.3% versus 6.9% in Kaniyambadi and Nova Scotia, respectively. SGA rates were 46.9% in Kaniyambadi and 7.5% in Nova Scotia when the Canadian fetal growth standard was used to define SGA and 6.7% in Kaniyambadi and < 1% in Nova Scotia when the Indian standard was used. In Kaniyambadi, low birth weight, preterm birth and perinatal mortality rates did not decrease between 1990 and 2005. SGA rates in Kaniyambadi declined significantly when SGA was based on the Indian standard but not when it was based on the Canadian standard. Maternal mortality rates fell by 85% (95% confidence interval 57% to 95%) in Kaniyambadi between 1986–90 and 2001–05. Perinatal mortality rates were 11.7 and 2.6 per 1,000 total births and cesarean delivery rates were 6.0% and 20.9% among live births ≥ 2,500 g in Kaniyambadi and Nova Scotia, respectively.ConclusionHigh rates of fetal growth restriction and relatively high rates of preterm birth are responsible for the high rates of low birth weight in South Asia. Increased emphasis is required on health services that address the morbidity and mortality in all birth weight categories.

Pregnant? Quitting Smoking Early Matters

Maternal smoking has been associated with higher rates of preterm births and small-for-gestational-age (SGA) babies; however, whether quitting smoking early during pregnancy can diminish these adverse outcomes is unknown. In a prospective study of 2500 nulliparous women in New Zealand and Australia, investigators assessed pregnancy outcomes in three cohorts based on self-reported smoking status: …

Rate of preterm births in pregnant women with common lower genital tract infection: a population-based study based on the clinical practice

Objective. To estimate the rate of preterm births in pregnant women with lower genital tract infection, i.e. vulvovaginitis-bacterial vaginosis and to check their prevention by drug treatments in the usual clinical practice.Method. The rate of preterm birth of pregnant women with or without lower genital tract infection was evaluated in the population-based large data set of the Hungarian Case–Control Surveillance of Congenital Abnormalities. Only prospectively and medically recorded diagnoses of vulvovaginitis-bacterial vaginosis were evaluated.Results. Of 38,151 newborn infants, 2698 (7.1%) had mothers with vulvovaginitis-bacterial vaginosis diagnosed in early pregnancy and the rate of preterm births was 7.5% among them, while this figure was 9.3% in babies born to mothers without these recognized genital infections. After early diagnosis and treatment of vulvovaginitis-bacterial vaginosis, clotrimazole and ampicillin seemed to be most effective to reduce the preterm birth during the study period. However, the rate of preterm births was lower in babies born to mothers without recorded vulvovaginitis-bacterial vaginosis but treated by clotrimazole and ampicillin (7.2–7.8%) as well.Conclusion. The lower rate of preterm births in babies born to mothers with vulvovaginitis-bacterial vaginosis may be explained by their effective treatment. However, the high rate of preterm births in pregnant women without genital tract infection and antimicrobial treatment may be connected with asymptomatic or unrecognized symptomatic and untreated vaginal infections.

Utilization of Health Care Services of Pregnant Women Complicated by Preeclampsia in Ontario

Objective: To assess the utilization of health care services by pregnant women affected by preeclampsia (PE). Design: Population-based study. Setting: Perinatal partnership hospitals in Ontario. Population: Obstetric deliveries in 2005 Canadian province of Ontario (about 95% of births). Methods: For each PE case, four subjects without PE matched by age, parity, plurality, and hospital at childbirth were chosen as the controls. We compared the utilization of intra-partum care services and infant outcomes between the two groups. We also estimated the extra costs to the health care system in Ontario for caesarean delivery and caring of extremely low birth weight infants attributable to PE during the neonatal period and in the first 2 years of life. Main Outcome Measures: Cesarean delivery, hospital stay, extremely low birth weight infants, cost. Results: Of the 120,611 obstetric deliveries included in this analysis, 1240 (1.3%) were diagnosed with PE. Patients with PE and matched controls were similar in maternal age, parity, and other demographic characteristics. Compared with study subjects without PE, those with PE had increased uses of spinal anesthesia, maternal transfer, Cesarean delivery, labour induction, neonatal transfer, newborn resuscitation, longer hospital stay for childbirth, and higher rates of preterm births and low birth weight. The extra costs to the health care system for cesarean delivery and caring of extremely low-birth-weight infants attributable to PE during the neonatal period and in the first 2 years of life in Ontario were $0.5 millions, 3.1 millions, and $5.1 million per year, respectively, if we use the reported PE rate in this database. Conclusion: PE is associated with substantially increased costs to the health care system.

Booking status and caesarean section outcome in LAUTECH teaching hospital, Osogbo

Antenatal care is concerned mainly with prevention, early diagnosis and treatment of general medical and pregnancy associated disorders. Quality of care varies across health facilities; the booking status of the women who deliver would have influence on the pregnancy outcome. A comparative study of caesarean section outcome among the booked and unbooked mothers delivered at Ladoke Akintola University Teaching Hospital, Osogbo. Mean age of the women was 29.7 +/- 5.9 years. The booked mothers were older than the unbooked mothers. All the maternal deaths were among the unbooked mothers. There were higher rates of preterm birth, neonatal asphyxia and neonatal admissions to intensive care units among the babies delivered by unbooked mothers compared to the booked mothers. Unbooked women and their babies are at higher risks of caesarean section complications than the booked mothers.

Are Racial Disparities in Preterm Birth Larger in Hypersegregated Areas?

The causes of the racial/ethnic disparity in preterm birth (PTB) remain largely unknown; traditional risk factors such as smoking and prenatal care fail to account for it. The authors examined whether living in metropolitan areas (MAs) with high levels of residential racial segregation along multiple dimensions (hypersegregation) was associated with higher rates of PTB or larger racial disparities in PTB and whether segregation modified the established race-age association in PTB. The authors merged 2000 natality data (n = 1,944,703) with US Census measures of Black-White hypersegregation. They executed two-level hierarchical logistic regression analyses among White and Black mothers in 237 MAs to estimate the odds of PTB by hypersegregation, race, and age, after controlling for covariates. In unadjusted and adjusted models, Black infants in hypersegregated MAs were more likely to be preterm than Black infants in nonhypersegregated MAs (p < 0.001). Black-White PTB disparities were larger in hypersegregated areas than in nonhypersegregated areas (p < 0.001), and the age-race association with PTB was modified by hypersegregation (p < 0.001). Living in a hypersegregated MA had a more pronounced association with PTB among older Black women, and racial disparities in PTB were larger in hypersegregated areas among older mothers (p < 0.001). Since over 40% of Black childbearing women live in hypersegregated areas, residential segregation may be an important social determinant of racial birth disparities.

Maternal acute respiratory infectious diseases during pregnancy and birth outcomes

The objective of the study was to evaluate the possible association between maternal acute respiratory infectious diseases (ARID) during pregnancy and birth outcomes. Newborn infants born to mothers with or without ARID as reference were compared in the population-based large data set of newborns without any defect in the Hungarian Case-Control Surveillance System of Congenital Abnormalities. Main outcome measures were birth weight and gestational age at delivery, in addition the rate of preterm births and low birthweight newborns. Of 38,151 newborns, 3,455 (9.1%) had mothers with ARID during pregnancy which were differentiated according to six manifestations from sinusitis to the pneumonia. Mothers with ARID in pregnancy had a longer (0.3 week) gestational age at delivery (adjusted t = 5.4; p < 0.0001) and a lower rate of preterm births (6.7% vs. 9.4%) [adjusted odds ratio (OR) with 95% confidence interval (CI): 0.72, 0.63-0.83] than mothers without ARID. However, severe ARID (bronchitis-bronchiolitis and particularly pneumonia) associated with a higher rate of preterm births (13.0%, adjusted OR with 95% CI: 1.4, 1.1-1.8), while mild ARID (sinusitis, pharyngitis, tonsillitis, laryngitis-tracheitis) resulted in a lower rate of preterm births (5.5%, adjusted OR with 95% CI: 0.5, 0.4-0.7). In conclusion, there was an obvious correlation between severity of ARID in pregnant women and rate of preterm births.

Cervical Salvage Cerclage

Cervical cerclage is used to manage women at high risk of late miscarriage (LM) and spontaneous preterm birth (PTB) due to factors such as history of cervical insufficiency (CI), uterine anomaly, cervical surgery and ultrasound (US) diagnosed cervical shortening. Urinary tract infection (UTI) and subsequent pyelonephritis, and bacterial infection are associated with PTB, but their role in PTB after cervical cerclage is unknown. We examined the relationship between UTI and bacterial vaginosis (BV), fetal fibronectin (fFN) test and PTB in women undergoing elective- or US-indicated cervical cerclage. We also investigated whether fetal fibronectin (fFN) test were useful to predict PTB.This is a single center, retrospective study of singleton pregnant women at PTB clinic, University College London Hospital (UCLH, 2005–2015) who underwent elective or US-indicated cervical cerclage. Women were tested for UTI and BV before cerclage placement and received mid-gestation fFN testing. Patient data were extracted from the PTB clinic database and electronic records. Statistical analyses used Pearson’s chi-square and Mann-Whitney U tests. P values were corrected by Bonferroni method as required.267 singleton pregnant women attended our clinic with completed birth outcome. Of those, 32.2% (86/267) delivered prematurely. All women with UTI or BV received antibiotic treatment. Women with a UTI before cerclage placement were more likely to deliver preterm when compared to those with negative MSU culture (OR 3.39, 95%CI 1.24-9.27, p = 0.04). Their gestational age at delivery were also lower than those with negative MSU result (36+6, IQR 31+4-38+2week vs 38+1, IQR 36+1-39+5-week, p = 0.05). However, UTI after cerclage placement or BV either before or after cerclage placement were not associated with PTB. Women who had a positive fFN result were more likely to deliver preterm (OR 3.85, 95% CI 1.81–8.41, p = 0.0007).The presence of a UTI before cervical cerclage is associated with a higher rate of PTB in women who receive a cervical cerclage, even when treated. We did not find an association between pre or post-cerclage BV or post-cerclage UTI and PTB. Further research is needed to elucidate the link between UTI and PTB in women undergoing cervical cerclage.

Maternal Work and Birth Outcome Disparities

We tested relations between aspects of maternal work and birth outcomes in a national sample and in subgroups known to experience disparities. Three indices of work attributes (Status and Recognition, Physical Demands, and Exposure to Conflict) were derived by factor analysis of variables extracted from the Department of Labor's O*Net database. The indices were linked to the National Longitudinal Survey of Youth using occupation codes for the primary jobs held by women who gave birth between 1979 and 2000 and worked during the quarter prior to birth (n = 3,386 births to n = 2,508 mothers). Multiple regression was used to model birth outcomes as functions of the work attribute indices, controlling for several measures of socioeconomic status and risk factors for adverse birth outcomes. In the full sample, work-related Physical Demands were associated with lower average birthweight and increased odds of preterm birth while Status and Recognition was associated with higher average birthweight and lower odds of fetal growth restriction. In stratified models, Status and Recognition was associated with higher birth weight among women with low (versus high) income and with lower odds of preterm birth among women with low (versus high) education. Physical Demands were associated with higher rates of preterm birth among women with low (versus high) income and education and among African-American mothers (compared to Whites). The work environment is an important predictor of healthy births. Relations between maternal work attributes and birth outcomes differ by race/ethnicity and socioeconomic status and according to the outcome under investigation. Further research with measures of work attributes specific to maternal work experiences is recommended to confirm our findings.

The “Hispanic paradox”: an investigation of racial disparity in pregnancy outcomes at a tertiary care medical center

The purpose of this study was to examine racial disparities and the "Hispanic paradox" in pregnancy outcomes at a tertiary-care medical center. A cross-sectional study of pregnancy events was performed with information from the Duke University birth database. The latter includes data on birth outcomes, cost, and health services factors. The final sample included 10,755 women with Medicaid insurance, who gave birth during calendar years 1994-2004. Pregnancy comorbidities and outcome measures were identified by International Classification of Diseases, 9th revision, and Current Procedural Terminology (CPT) codes. Univariate and multivariate analyses were performed to compare racial/ethnic groups. African-American women were younger and more likely to be employed, to have a medical comorbidity, to remain in the hospital for >4 days, and to have hospital charges of >$7500. African-American women had higher rates of preterm birth, small-for-gestational-age infants, preeclampsia, and stillbirths. There were no differences by race for gestational diabetes mellitus. With the use of white women as the reference group, Hispanic women had lower odds for preterm birth (odds ratio, 0.66; 95% CI, 0.54-0.80), and African-American women had greater odds for preeclampsia (odds ratio, 1.30; 95% CI, 1.07-1.58) and small-for-gestational-age infants (odds ratio, 1.74; 95% CI, 1.29-2.36). With the use of African-American women as the reference, Hispanic women were less likely than African-American women to experience any adverse pregnancy event, with the exception of gestational diabetes mellitus. Poverty and insurance status does not explain differences in adverse pregnancy outcomes between African-American women and Hispanic women with Medicaid insurance.

Cutaneous Leishmaniasis during Pregnancy: Exuberant Lesions and Potential Fetal Complications

Cutaneous leishmaniasis affects millions of people worldwide. After observations of atypical lesions in pregnant women at the health centers of Corte de Pedra, Brazil, 9 years of records were reviewed, and 26 pregnant patients were identified. A retrospective case-control study revealed that lesions in pregnant women were much larger than those in nonpregnant patients in an age- and sex-matched group (mean area, 6.08 cm2 vs. 1.46 cm2; P=.008), and many lesions had an exophytic nature. Despite foregoing treatment until after delivery, response to pentavalent antimony therapy was favorable (rate of cure with 1 course of treatment, 85%). High rates of preterm births (10.5%) and stillbirths (10.5%) were reported. Cutaneous leishmaniasis during pregnancy produces distinct lesions and may have adverse fetal effects.

Reconciling the High Rates of Preterm and Postterm Birth in the United States

Preterm and postterm birth rates are substantially higher in the United States than in Canada and other industrialized countries, although relative mortality at preterm compared with term gestation is considerably lower. We attempted to explain these differences based on differences in the method of gestational age estimation. We used information on all live births in the United States and Canada for 1995-2002 and on singleton births and perinatal deaths for 1996-1999. Gestational age in Canada was based on the clinical estimate, whereas in the United States both menstrual-based and clinical estimates were used. In 2002, preterm (12.3%) and postterm birth (6.6%) rates in the United States were far higher than in Canada (7.6% and 1.0%, respectively) when U.S. rates were based on menstrual dates. Differences were reduced or abolished when U.S. rates were based on the clinical estimate of gestation (10.1% and 1.0%, respectively). In Canada, the rate ratio for perinatal death at preterm compared with term gestation was 27.8 (95% confidence interval [CI] 26.3-29.3), similar to that in the United States when gestation was based on the clinical estimate (rate ratio 26.5, 95% CI 26.1-26.9, P value for difference in rate ratios=.06) but not when based on menstrual dates (rate ratio 18.9, 95% CI 18.7-19.2, P<.001). Menstrual dates in U.S. data misclassify gestational duration and overestimate both preterm and postterm birth rates. For international comparisons, gestational age in the United States should be based on the clinical estimate. II.

Pregnancy complications and birth outcomes of pregnant women with urinary tract infections and related drug treatments

Maternal urinary tract infections in pregnancy showed an association with a higher rate of preterm birth in previous studies. The aim of this study was to check this relationship, and in addition to evaluate the efficacy of recent medical treatments. The population-based large control (without any defects) data set of the Hungarian Case-Control Surveillance System of Congenital Abnormalities was evaluated. Of 38,151 newborn infants, 2188 (5.7%) had mothers with urinary tract infections during pregnancy, and 90% of these maternal diseases were prospectively and medically recorded. The prevalence of pre-eclampsia and polyhydramnios showed an association with urinary tract infections during pregnancy. Pregnant women with urinary tract infections in pregnancy had a somewhat shorter gestational age (0.1 week) and a higher proportion of preterm births (10.4% vs 9.1%). These differences were correlated with the severity of urinary tract infections. However, the preterm-inducing effect of maternal urinary tract infections is preventable by some antimicrobial drugs such as ampicillin, cefalexin and cotrimoxazole. In conclusion, maternal urinary tract infections during pregnancy increase pre-eclampsia and polyhydramnios, and in addition the rate of preterm birth; however, the latter is preventable by appropriate drug treatments.