Cocaine and cigarettes: a comparison of risks

Summary. In order to provide additional data and perspective to current clinical, policy, and legal debates surrounding the prenatal use of cocaine in the USA, a retrospective cohort study was conducted to examine effects of cocaine on selected perinatal outcomes, and to compare the relative risks of adverse perinatal outcomes among users of cocaine and users of cigarettes. Using data from a large urban perinatal registry, relative risks of selected perinatal outcomes were determined for maternal cocaine users who were non-smokers of cigarettes, and used no marijuana, heroin, amphetamines, or alcohol (n = 64), and for cigarette smokers who do not use illicit drugs or alcohol during pregnancy (n = 3209). When compared with women with no recorded prenatal exposure to drugs or cigarettes (n = 13043), cocaine users had higher risks than smokers for the following adverse outcomes: low birthweight [Relative Risk (RR) 5.3, 95% Confidence Interval (CI) 3.0–9.3], small-for-ges-tational age (SGA) [RR4.2, 95% CI 2.4–7.3], prematurity [RR4.0, 95% CI 2.3–7.0], abruptio placentae [RR = 10.0,95% CI 3.5–29.0], placenta prae-via [RR = 2.4, 95% CI 0.3–17.8] and perinatal death [RR = 5.3, 95% CI 1.9–15.2]. Smokers who did not use any drugs experienced most of the same adverse perinatal outcomes as cocaine users, but the magnitude of risk was greater in cocaine users than in smokers for all outcomes. However, given the greater numbers of cigarette smokers than cocaine users in the population the numbers of infants in the population suffering these adverse outcomes is likely to be greater among offspring of cigarette smokers. The data support current concern about the risk of cocaine, and current efforts to provide treatment to pregnant cocaine users. The data also underline the continued substantial risks of cigarette smoking to large numbers of pregnant women.     

Recreational drug use and the risk of primary infertility

Recreational drug (marijuana, lysergic acid diethylamide or LSD, speed, cocaine, and "other") exposures of women with primary infertility were compared with those of a matched control group of women with proven fertility. Women who reported smoking marijuana had a slightly elevated risk for infertility due to an ovulatory abnormality (RR = 1.7, 95% CI = 1.0 to 3.0). The risk was greatest among women who had used marijuana within one year of trying to become pregnant (RR = 2.1, 95% CI = 1.1 to 4.0). No consistent frequency or duration of use effects could be demonstrated, and the risk was confined to low-frequency users. Risks associated with the use of other drugs were not elevated. The risk of infertility from a tubal abnormality associated with cocaine use was greatly increased (RR = 11.1, 95% CI = 1.7 to 70.8). Our results are consistent with animal studies suggesting that smoking marijuana may cause a transient disruption of ovulatory function. The possibility that cocaine exposure influences the development of tubal infertility needs further investigation.     

Conjugated estrogen use and risk of endometrial cancer

The relation between use of conjugated estrogens and the risk of uterine cancer was examined among 188 white women with newly diagnosed endometrial cancer and 428 controls hospitalized for nonmalignant conditions requiring surgery at the Boston Hospital for Women-Parkway Division, Boston, Massachusetts, in January 1970-June 1975. As in prior studies, the greatest increases in risk were associated with dosages of 0.625 mg or greater (relative risk (RR) = 3.8, 95% confidence interval (CI) = 2.2-6.6) and duration of use of 10 or more years (RR = 7.6). Risk was elevated whether or not use was cyclic. Cyclic use was associated with a higher risk (RR = 3.6, 95% CI = 2.2-6.6) than continuous use (RR = 2.4, 95% CI = 1.3-4.1), but the difference between these risk estimates was not statistically significant. Risk remained increased even among women who had discontinued use of conjugated estrogens five or more years previously (RR = 4.5). Cases who were previous users had less advanced lesions at diagnosis than had never users. The highest risk associated with use of conjugated estrogens was that for stage I, grade 1 disease with no myometrial invasion. However, increases in risk of more advanced disease were seen among long-term users.     

Risk factors for neonatal seizures: a population-based study, Harris County, Texas, 1992-1994.

Risk factors for neonatal seizures were evaluated in 116,048 infants born between 1992 and 1994 to residents of Harris County, Texas; 207 of these infants were diagnosed with clinical neonatal seizures. Information was obtained from the infant's birth certificate to assess the relation between seizures and birth weight, gender, ethnicity, place of birth, mother's age, method of delivery, parity, and multiple births. These factors were evaluated by univariate and multivariate analysis using logistic regression. For preterm infants, a birth weight of <1,500 g was the strongest risk factor (relative risk (RR) = 9.1, 95% confidence interval (CI): 4.7, 17.5), followed by birth in a private/university hospital (RR = 2.8, 95% CI: 1.5, 5.0) and male gender (RR = 1.8, 95% CI: 1.0, 3.4). For term infants, significant risk factors included birth by cesarean section (RR = 2.2, 95% CI: 1.5, 3.2), small birth weight for gestational age (RR = 1.9, 95% CI: 1.2, 2.9), birth in a private/university hospital (RR = 1.8, 95% CI: 1.1, 3.0), and maternal age of 18-24 compared with 25-29 years (RR = 1.6, 95% CI: 1.1, 2.3). Birth by assisted vaginal delivery and primiparity were marginally significant for term infants. Birth weight is a significant risk factor for neonatal seizures. The role of perinatal complications warrants further evaluation.     

A prospective study of pregravid oral contraceptive use and risk of hypertensive disorders of pregnancy

Oral contraceptive use is associated with hypertension, dyslipidemias, and insulin resistance, all of which also characterize hypertensive disorders of pregnancy. In this prospective cohort study, the association of oral contraceptive use before pregnancy and the risk of gestational hypertension and preeclampsia was assessed. Between 1991 and 1995, 3973 nulliparous women who reported their first pregnancy lasting > or = 6 months were studied. Pregravid exposures were collected by biennial mailed questionnaires, and cases were confirmed by medical record review. Recent oral contraceptive use was defined as use within 2 years of pregnancy. Proportional hazards analysis was used to adjust for potential confounding variables. During the 4 years of follow-up, 133 (3.3%) women with gestational hypertension and 62 (1.6%) with preeclampsia were identified. Twenty-five percent of women who did not develop these disorders were recent users of oral contraceptives, compared with 19% (p = 0.11) of women who developed gestational hypertension and 30% (p = 0.38) who developed preeclampsia. Mean duration of prior oral contraceptive use was similar for cases and noncases. Compared with never and past users, the multivariate relative risk among recent users for developing gestational hypertension was 0.7 (95% confidence interval (CI), 0.4-1.0) and for preeclampsia was 1.3 (95% CI, 0.8-2.4). Among recent users who had used oral contraceptives for > or = 8 years, the relative risk for gestational hypertension was 0.6 (95% CI, 0.3-1.2) and for preeclampsia was 2.1 (95% CI, 1.1-4.2). When the analysis was restricted to women who had never smoked, the risk for gestational hypertension was 0.2 (95% CI, 0.1-0.9) and for preeclampsia was 4.1 (95% CI, 1.9-8.7). Thus, recent use of oral contraceptives was associated with a reduced risk for developing gestational hypertension. In contrast, there was a suggestion that recent use was associated with an increased risk of developing preeclampsia, but only among women who had used these agents for > or = 8 years.     

The role of poultry and meats in the etiology of Campylobacter jejuni/coli enteritis.

To determine the role of meats as possible sources of infection leading to Campylobacter jejuni/coli (CJC) enteritis, 218 cases and 526 controls were selected from the King County Group Health Cooperative (GHC) population from April 1982 through September 1983. All subjects were interviewed regarding food consumption one week prior to case onset. Consumption of chicken and cornish game hen were both associated with more than a doubling of the risk of CJC enteritis: for chicken (relative risk = 2.4, 95% CI = 1.6-3.6), and for game hen, (RR = 3.3, 95% CI = 1.1-9.8). The consumption of raw or rare chicken was even more strongly associated (RR = 7.6, 95% CI = 2.1-27.6). Strains of CJC bearing R factors for tetracycline were equally as likely as tetracycline-susceptible strains to have been acquired from chicken and game hens. Processed turkey sandwich meats (RR = 1.7, 95% CI = 1.0-2.9) raw or rare fish (RR = 4.0, 95% CI = 1.1-14.5) and shellfish (RR = 1.5, 95% CI = 1.1-2.1) were the only other meats reported to have been eaten significantly (p less than .05) more often by cases than by controls. These data along with the results of bacteriologic sampling of meats from King County retail food markets during the same period suggest that ingestion of contaminated chicken is a primary source of CJC enteritis, contributing to approximately half of the cases.     

Maternal smoking and the risk of polyhydramnios.

BACKGROUND. Washington State birth certificates were used to conduct a population-based case-control study to assess the possible association of maternal smoking with polyhydramnios. METHODS. All singleton births complicated by polyhydramnios (n = 557) were identified from the vital records for the years 1984 to 1987. For comparison, 1671 records were randomly selected for the same years from singleton births uncomplicated by polyhydramnios. RESULTS. Women who reportedly smoked prenatally were found to be at increased risk for polyhydramnios (relative risk [RR] = 1.7, 95% confidence interval [CI] = 1.5-2.1, adjusted for marital status, maternal age, and parity). When women with conditions known to be associated with polyhydramnios were excluded, the risk for those who smoked prenatally remained elevated (RR = 1.8, 95% CI = 1.1-2.3). CONCLUSION. Overdistention of the uterus from polyhydramnios may cause a variety of pregnancy complications. The observed association of smoking with polyhydramnios may be a further indication for public health interventions aimed at preventing smoking during pregnancy.     

Rates and relative risk of hospital admission among women in violent intimate partner relationships

OBJECTIVES: This study assessed the history of hospitalization among women involved in violent intimate relationships. METHODS: In this 1-year retrospective cohort study, female residents of King County, Washington, who were aged 18 to 44 years and who had filed for a protection order were compared with nonabused women in the same age group. Outcome measures included overall and diagnosis-specific hospital admission rates and relative risk of hospitalization associated with abuse. RESULTS: Women known to be exposed to a violent intimate relationship were significantly more likely to be hospitalized with any diagnosis (age-specific relative risks [RRs] ranging from 1.2 to 2.1), psychiatric diagnoses (RR = 3.6, 95% confidence interval [CI] = 2.8, 4.6), injury and poisoning diagnoses (RR = 1.8, 95% CI = 1.2, 2.8), digestive system diseases (RR = 1.9, 95% CI = 1.3, 2.9), and diagnoses of assault (RR = 4.9, 95% CI = 1.1, 22.1) or attempted suicide (RR = 3.7, 95% CI = 1.6, 9.2) in the year before filing a protection order. CONCLUSIONS: This study showed an increased relative risk of both overall and diagnosis-specific hospitalizations among abused women. Intimate partner violence has a significant impact on women's health and use of health care.     

Relative risk of upper gastrointestinal complications among users of acetaminophen and nonsteroidal anti-inflammatory drugs

Nonsteroidal anti-inflammatory drugs (NSAIDs) have been associated with an increase in upper gastrointestinal complications. There is no agreement, however, on whether all conventional NSAIDs have a similar relative risk (RR), and epidemiologic data are limited on acetaminophen. We studied the association between these medications and the risk of upper gastrointestinal bleed/perforation in a population-based cohort of 958,397 persons in the United Kingdom between 1993 and 1998. Our nested case-control analysis included 2,105 cases and 11,500 controls. RR estimates were adjusted for several factors known to be associated with upper gastrointestinal bleed/perforation. Compared with non-users, users of acetaminophen at doses less than 2 gm did not have an increased risk of upper gastrointestinal complications. The adjusted RR for acetaminophen at doses greater than 2 gm was 3.6 [95% confidence interval (95% CI) = 2.6-5.1]. The corresponding RRs for low/medium and high doses of NSAIDs were 2.4 (95% CI = 1.9-3.1) and 4.9 (95% CI = 4.1-5.8). The RR was 3.1 (95% CI = 2.5, 3.8) for short plasma half-life, 4.5 (95% CI = 3.5-5.9) for long half-life, and 5.4 (95% CI = 4.0-7.1) for slow-release formulations of NSAIDs. After adjusting for daily dose, the differences in RR between individual NSAIDs tended to diminish except for apazone. Users of H2 receptor antagonists, omeprazole, and misoprostol had RRs of 1.4 (95% CI = 1.2-1.8), 0.6 (95% CI = 0.4-0.9), and 0.6 (95% CI = 0.4-1.0), respectively. Among NSAID users, use of nitrates was associated with an RR of 0.6 (95% CI = 0.4-1.0).     

Do Supervised Injecting Facilities Attract Higher-Risk Injection Drug Users?

BACKGROUND: In Western Europe and elsewhere, medically supervised safer injection facilities (SIFs) are increasingly being implemented for the prevention of health- and community-related harms among injection drug users (IDUs), although few evaluations have been conducted, and there have been questions regarding SIFs' ability to attract high-risk IDUs. We examined whether North America's first SIF was attracting IDUs who were at greatest risk of overdose and blood-borne disease infection. METHODS: We examined data from a community-recruited cohort study of IDUs. The prevalence of SIF use was determined based on questionnaire data obtained after the SIF's opening, and we determined predictors of initiating future SIF use based on behavioral information obtained from questionnaire data obtained before the SIF's opening. Pearson's chi-square test was used to compare characteristics of IDUs who did and did not subsequently initiate SIF use. RESULTS: Overall, 400 active injection drug users returned for follow-up between December 1, 2003 and May 1, 2004, among whom 178 (45%) reported ever using the SIF. When we examined behavioral data collected before the SIF's opening, those who initiated SIF use were more likely to be aged <30 years (odds ratio [OR]=1.6, 95% confidence interval [CI]=1.0-2.7], p=0.04); public injection drug users (OR=2.6, 95% CI=1.7-3.9, p<0.001); homeless or residing in unstable housing (OR=1.7, 95% CI=1.2-2.7, p=0.008); daily heroin users (OR=2.1, 95% CI=1.3-3.2, p=0.001); daily cocaine users (OR=1.6, 95% CI=1.1-2.5, p=0.025); and those who had recently had a nonfatal overdose (OR=2.7, 95% CI=1.2-6.1, p=0.016). CONCLUSIONS: This study indicated that the SIF attracted IDUs who have been shown to be at elevated risk of blood-borne disease infection and overdose, and IDUs who were contributing to the public drug use problem and unsafe syringe disposal problems stemming from public injection drug use.     

Maternal and infant birth characteristics and hepatoblastoma

Hepatoblastoma is a rare embryonal tumor with unknown etiology. The authors conducted a case-cohort study using public health surveillance data sets to examine perinatal risk factors for hepatoblastoma. Hepatoblastoma cases (n = 58) diagnosed between 1985 and 2001 were identified from the New York State Cancer Registry and were matched to electronic birth records for 1985-2001 from New York State, excluding New York City. Controls (n = 6,056) were selected from the birth cohorts for the same years. Having a birth weight less than 1,000 g was associated with a strongly increased risk of hepatoblastoma (relative risk (RR) = 56.9, 95% confidence interval (CI): 24.0, 130.7). After adjustment for birth weight, a moderately increased risk of hepatoblastoma was found for younger maternal age (<20 years vs. 20-29 years: RR = 2.5, 95% CI: 1.0, 5.5), presumptive use of infertility treatment (RR = 9.2, 95% CI: 2.1, 31.5), maternal smoking (RR = 2.1, 95% CI: 1.0, 4.2), and higher maternal prepregnancy body mass index (body mass index of 25-29 vs. 20-24: RR = 2.9, 95% CI: 1.2, 7.6).     

Clinical significance of subchorionic and retroplacental hematomas detected in the first trimester of pregnancy

AIMS: To evaluate the long-term clinical significance of intrauterine hematomas detected in the first trimester of pregnancy in a general obstetric population. METHODS: A prospective study was designed to compare the perinatal outcome in 187 pregnant women with intrauterine hematomas to 6488 controls in which hematomas were not detected at first trimester by ultrasound examination. RESULTS: The incidence of intrauterine hematoma in the first trimester in a general obstetric population was 3.1%. A retroplacental position of the hematoma was significantly correlated with an increased risk for adverse maternal and neonatal complications. The presence or absence of symptoms of threatened abortion did not affect these outcomes. The rates of operative vaginal delivery (RR: 1.9; CI: 1.1-3.2) and cesarean section (RR: 1.4; CI: 1.1-1.8) were significantly greater in the hematoma group as compared to the control group, as well as the rates of pregnancy induced hypertension (RR: 2.1; CI: 1.5-2.9) and preeclampsia (RR: 4.0; CI: 2.4-6.7). Placental abruption (RR: 5.6; CI: 2.8-11.1), and the incidence of placental separation abnormalities was also significantly more frequent in the hematoma group (RR: 3.2; CI: 2.2-4.7). Perinatal complications, including the rate of preterm delivery (RR: 2.3; CI: 1.6-3.2), intrauterine growth restriction (RR: 2.4; CI: 1.4-4.1), fetal distress (RR: 2.6; CI: 1.9-3.5), meconium stained amniotic fluid (RR: 2.2; CI: 1.7-2.9), and NICU admission (RR: 5.6; CI: 4.1-7.6) were also significantly increased in this group. Furthermore, the frequency of intrauterine demise and perinatal mortality was increased in the hematoma group, but this difference did not reach statistical significance (p = 0.6 and p = 0.2). CONCLUSION: The authors' study suggests that the presence of an intrauterine hematoma during the first trimester may identify a population of patients at increased risk for adverse pregnancy outcome.     

Urban and rural suicide differentials in migrants and the Australian-born, New South Wales, Australia 1985--1994.

We estimated risk of suicide in adults in New South Wales (NSW) by sex, country of birth and rural/urban residence, after adjusting for age; we also examined youth suicide (age 15-24 years). The study population was the entire population of NSW, Australia, aged > or =15 years during the period 1985-1994. Poisson regression was used to examine the relationship between predictor variables and the risk of suicide, with the focus on migrant status and area of residence. A significantly higher risk of suicide was found in male migrants from Northern Europe and Eastern Europe/former USSR, compared to Australian-born males; a significantly lower suicide risk occurred in males from Southern Europe, the Middle East and Asia. In female migrants, those from UK/Eire, Northern Europe, Eastern Europe/former USSR and New Zealand exhibited a significantly higher risk of suicide compared to Australian-born females. A significantly lower risk of suicide occurred in females from the Middle East. Male migrants overall were at significantly lower risk of suicide than the Australian-born, while female migrants overall had a significantly higher risk of suicide than Australian-born females. Among migrant males overall, the rural-urban suicide risk differential was significantly higher for those living in non-metropolitan areas (RR = 1.9; 95% CI: 1.7-2.1). Suicide risk was significantly higher in non-metropolitan male immigrants from the UK/Eire (RR = 1.4; 95% CI: 1.1-1.7), Southern Europe (RR = 1.7; 95% CI: 1.2-2.4), Northern/Western Europe (1.5; 95% CI: 1.2-1.9), the Middle East (RR = 3.8; 95% CI: 1.9-7.8), New Zealand (RR = 1.4; 95% CI: 1.0-1.8) and 'other' (RR = 2.6; 95% CI: 1.9-3.5), when compared to their urban counterparts. There was no statistically significant difference in suicide risk between rural and urban Australian-born males. For female suicide, significantly lower risk was found in female immigrants living in non-metropolitan areas who were from Northern/Western Europe (RR = 0.7; 95% CI: 0.4-0.96), as well as the Australian-born (RR = 0.7; 95% CI: 0.6-0.8), when compared to their urban counterparts. The non-metropolitan/metropolitan relative risk for suicide in female migrants overall was not significantly different from one. Among male youth there was a significantly higher suicide risk in non-metropolitan areas, with a relative risk estimate of 1.4 for Australian-born youth (95% CI: 1.2-1.5) and 1.7 for migrant youth (95% CI: 1.2-2.4), when compared with metropolitan counterparts. We conclude that suicide among migrant males living in non-metropolitan areas accounts for most of the excess of male suicide in rural NSW, and the significantly lower risk of suicide for non-metropolitan Australian-born women does not apply to migrant women.     

Predictors of accidental fatal drug overdose among a cohort of injection drug users

OBJECTIVES: This study evaluated factors associated with accidental fatal drug overdose among a cohort of injection drug users (IDUs). METHODS: In a prospective cohort study of 2849 IDUs in King County, Washington, deaths were identified by electronically merging subject identifiers with death certificate records. Univariate and multivariate Cox regression analyses were performed to identify predictors of overdose mortality. RESULTS: Thirty-two overdoses were observed. Independent predictors of overdose mortality were bisexual sexual orientation (relative risk [RR] = 4.86; 95% confidence interval [CI] = 2.30, 13.2), homelessness (RR = 2.30; 95% CI = 1.06, 5.01), infrequent injection of speedballs (RR = 5.36; 95% CI = 1.58, 18.1), daily use of powdered cocaine (RR = 4.84; 95% CI = 1.13, 20.8), and daily use of poppers (RR = 22.0; 95% CI = 1.74, 278). CONCLUSIONS: Sexual orientation, homelessness, and drug use identify IDUs who may benefit from targeted interventions.     

Relative efficacy of two acellular pertussis vaccines during three years of passive surveillance.

Prolonged unblinded passive surveillance of the trial cohort from the Swedish 1986-87 pertussis vaccine efficacy trial indicates that a two-component vaccine, containing pertussis toxoid and filamentous haemagglutinin, provided better long-term protection against pertussis than a monocomponent pertussis toxoid vaccine. The relative risk (RR) for culture-confirmed pertussis was 1.5 (95% confidence interval (CI) 1.0-2.4), and RR for pertussis according to parents' diagnoses was also 1.5 (95% CI 1.1-2.1), for the monocomponent vaccine compared with the two-component vaccine.     

Risk factors for hepatitis C virus infection. A case-control study of blood donors in the Trent Region (UK).

The introduction of screening for hepatitis C virus (HCV) by the National Blood Transfusion Service identified donors who had acquired HCV infection. We undertook a case-control study amongst blood donors in the Trent Region to determine risks for HCV infection. A total of 74 blood donors confirmed positive for hepatitis C infection and 150 age, sex and donor venue matched controls were included in the study. Fifty-three percent of hepatitis C infected blood donors reported previous use of injected drugs compared to no controls; relative risk (RR) not estimatable (lower limit 95% CI = 20). Other risk factors were a history of: receipt of a blood transfusion or blood products RR = 3.6 (95% CI 1.5-8.3), having been a ''health care worker'' RR = 2.8 (95% CI 1.1-7.6), tattooing RR = 3.3 (95% CI 1.2-8.7), and an association with having been born abroad RR = 3.2 (95% CI 1.1-9.5). No risk was shown for a history of multiple sexual partners, ear piercing or acupuncture. Injecting drug use explains more than 50% of hepatitis C infections in blood donors, a group who are less likely to have injected drugs than the general population.     

Partner violence during pregnancy and risk of adverse pregnancy outcomes

The purpose of this cross-sectional study was to investigate the association between partner physical or emotional abuse during pregnancy and pregnancy outcomes including perinatal death, low birthweight and preterm delivery. Women, aged 18-65, who attended one of two large primary care practices from 1997-98 were recruited for this study. Ever pregnant women were asked the frequency of abuse during each pregnancy and details of the pregnancy outcomes. Information regarding abuse during pregnancy and pregnancy outcomes was available for 755 women surveyed who reported a live birth or late fetal death, 14.7% indicated that an intimate partner was violent or abusive toward them during a pregnancy (274 of 1862 pregnancies). Abuse during pregnancy was significantly associated with an increased risk of perinatal death (adjusted relative risk [aRR] = 2.1, 95% confidence interval [CI] 1.3, 3.4) and, among live births, with preterm low birthweight (aRR = 2.4; 95% CI 1.5, 4.0) and term low birthweight (aRR = 1.9; 95% CI 1.0, 3.4). Greater abuse frequency was associated with increased risk. Abuse during pregnancy was associated with perinatal deaths and preterm low birthweight deliveries.     

Smoking and invasive cervical cancer risk. Results from a case-control study

The association between cigarette smoking and risk of invasive cervical cancer was investigated in a case-control study conducted in four hospitals in Leipzig, German Democratic Republic in 1983-1985. Analyses were based on 225 women aged 64 years or younger with newly diagnosed invasive cervical cancer and 435 age-matched controls with orthopedic or skin diseases. The crude relative risk of invasive cervical cancer was significantly elevated for women who had ever smoked (relative risk (RR) = 1.5, 95% confidence interval (CI) = 1.1-2.1). Adjustment for number of sexual partners reduced the risk to RR = 1.2 (95% CI = 0.8-1.6). Furthermore, the risk for smokers depended significantly on number of sexual partners (p less than 0.05) and was increased only among women with no partner or one partner (RR = 2.7, 95% CI = 1.2-6.1).     

Risks of induction of labour in uncomplicated term pregnancies

Our objective was to evaluate the risks of maternal and perinatal morbidity associated with induction of labour in uncomplicated term pregnancies. We conducted a retrospective cohort study including 7,430 women, not referred from another institution, with a single baby in vertex presentation, and delivering between 38 and 40 weeks of pregnancy. Among these women, 3,546 were excluded for prelabour pregnancy complications. Relative risks (RR), adjusted for parity, were computed to compare 3,353 women who went into labour spontaneously with 531 women whose labour was induced. Induction of labour was found to be associated with a higher risk of caesarean section [RR = 2.4, 95% CI 1.8, 3.4]. Use of non-epidural [RR = 1.5, 95% CI 1.2, 1.8] and of epidural analgesia [RR = 1.4, 95% CI 1.1, 1.7] was more frequent after labour induction. Resuscitation [RR = 1.2, 95% CI 1.0, 1.5], admission to the intensive care unit [RR = 1.6, 95% CI 1.0, 2.4] and phototherapy [RR = 1.3, 95% CI 1.0, 1.6] were more frequent after induction of labour. Results were similar when controlling simultaneously for parity, maternal age, gestational age, year of delivery, birthweight and the physician in charge of delivery in a logistic regression analysis. The results of this study suggests that induction of labour is associated with a higher risk of caesarean section and of some perinatal adverse outcomes. Induction of labour should be reserved for cases where maternal and perinatal benefits outweigh the risk of these complications.     

A case-control study of maternal smoking and congenital malformations

We conducted a population-based case-control study to assess the association between maternal smoking during pregnancy and the risk of giving birth to a child with a congenital malformation. Cases were all singleton livebirths with a congenital malformation recorded on the 1984-1986 Washington State Birth Records (n = 3284). The smoking histories of these mothers were compared to a randomly selected group of mothers with a singleton livebirth of a child without a malformation during these same years (n = 4500). When all malformations were taken as a group, there was no association with maternal smoking (relative risk (RR) = 1.0, 95% CI 0.9-1.1). However, increased risks were observed for a number of specific malformations, including microcephalus (RR = 2.0, 95% CI 1.0-4.0), cleft defects (RR = 1.4, 95% CI 1.0-2.0), and club foot (RR = 1.4, 95% CI 1.0-2.0). We did not find any association with Down's syndrome (RR = 0.8 95% CI 0.5-1.3) or any other malformation. We conclude that maternal smoking during pregnancy may be associated with an increased risk for some malformations.