Sven Cnattingius

Effects of maternal age, parity, and smoking on the risk of stillbirth

Objective To examine the effects of advanced maternal age, nulliparity, and smoking on risk of stillbirth as gestation advances, and to explore possible clinical mediators of these effects.

Comparison of umbilical-artery velocimetry and cardiotocography for surveillance of small-for-gestational-age fetuses

Intrauterine growth retardation is associated with an increased risk of fetal asphyxia as well as greater perinatal morbidity and mortality. Ultrasound fetometry enables detection of fetuses that are small for gestational age. Doppler velocimetry of the umbilical artery has good predictive ability for fetal distress, but it is not yet clear whether it could replace cardiotocography in antenatal surveillance of small-for-gestational-age fetuses. We have done a randomised comparison of the two methods. At four obstetric departments in Sweden, women with fetuses found to be small on ultrasound examination at 31 completed weeks of pregnancy or later were randomly assigned to antenatal surveillance with either doppler velocimetry (doppler; 214) or cardiotocography (CTG; 212). Pregnancies in the doppler group were managed according to a protocol based on blood-flow classes deriving from the semiquantitative evaluation of umbilical-artery velocity waveforms; unless the pregnancy was complicated by any other disorder, no antenatal cardiotocography was done. By comparison with the CTG group, the doppler group had fewer monitoring occasions (mean 4.1 [SD 3.1] vs 8.2 [6.2], p < 0.01), antenatal hospital admissions (68 [31.3%] vs 97 [45.8%], p < 0.01), inductions of labour (22 [10.3%] vs 46 [21.7%], p < 0.01), emergency caesarean sections for fetal distress (11 [5.1] vs 30 [14.2%], p < 0.01), and admissions to neonatal intensive care (76 [35.5%] vs 92 [43.4%], p = 0.10). The groups did not differ in gestational age at birth, birthweight, Apgar scores, or total number of caesarean deliveries. Umbilical-artery doppler velocimetry of small-for-gestational-age fetuses allows antenatal monitoring and obstetric interventions to be aimed more precisely than does cardiotocography.

Maternal and perinatal risk factors for childhood brain tumors (Sweden)

Childhood brain tumors (CBT) include a diversity of rare neoplasms of largely unknown etiology. To assess possible maternal and perinatal risk factors for CBT according to subtype, we carried out a nested (within Swedish birth-cohorts, 1973–89) case-control study, utilizing data from the nationwide Birth Registry. We ascertained incident brain tumor cases through linkage of the nationwide Birth and Cancer Registries and randomly selected five living controls from the former, matching each case on gender and birthdate. There were 570CBT cases, including 205 low grade astrocytomas, 58 high grade astrocytomas, 93 medulloblastomas, 54 ependymomas, and 160 ‘others.’ Risks for all brain tumors combined were elevated in relation to: (i) three maternal exposures-oral contraceptives prior to conception (odds ratios [OR]=1.6, 95 percent confidence interval [CI]=1.0–2.8), use of narcotics (OR=1.3, CI=1.0–1.6), or penthrane (OR=1.5, CI=1.1–2.0) during delivery); (ii) characteristics of neonatal distress (a combined variable including low one-minute Apgar score, asphyxia [OR=1.5, CI=1.1–2.0]) or treatments for neonatal distress (use of supplemental oxygen, ventilated on mask, use of incubator, scalp vein infusion, feeding with a jejunal tube [OR=1.6, CI=0.9–2.6]); and (iii) neonatal infections (OR=2.4, CI=1.5–4.0). Higher subtype-specific risks, observed for a few risk factors, did not differ significantly from the risk estimates for all subtypes combined for the corresponding risk factors. Childhood brain tumors were not associated significantly with other maternal reproductive, lifestyle, or disease factors; perinatal pain, anesthetic medications, birth-related complications; or with birthweight, birth defects, or early neonatal diseases. These findings suggest several new leads, but only weak evidence of brain tumor subtype-specific differences.

Depth of sleep and sleep habits among enuretic and incontinent children

In order to evaluate differences in sleep factors between children with wetting problems and dry children, questionnaire data were obtained from 1,413 schoolchildren between the ages of 6 and 10 y. The analyses were performed using logistic regression, and adjusted odds ratios (ORs) were calculated to approximate the relative risk. Current enuresis was associated with a subjectively high arousal threshold, pavor nocturnus, nocturia and confusion when awoken from sleep (ORs 2.7, 2.4, 2.1 and 3.4, respectively), whereas children with current incontinence often experienced bedtime fears, onset insomnia or nocturia (ORs 2.4, 2.3 and 2.7, respectively). Children exhibiting urinary urgency were overrepresented among both children with current enuresis (OR 2.5) and those with current incontinence (OR 17.2). It is concluded that impaired arousal mechanisms and bladder instability are aetiological factors underlying nocturnal enuresis. □Arousal, enuresis, incontinence, sleep

Sleep habits and sleep problems among a community sample of schoolchildren

Sleep habits, sleep problems and subjective depth of sleep among 1413 schoolchildren aged 6.2‐10.9 y were examined via a questionnaire, answered by the child and parent together. Total sleep time was approximately 10.5 h, with no difference between the sexes. Of 887 children who reported that they were awoken at night, parents considered that 75% were superficial sleepers and 25% were deep sleepers. The prevalence of frequent insomnia, sleepwalking and daytime sleepiness was 13, 7 and 4%, respectively. Logistic regression analyses indicated that onset insomnia was associated with fear of sleeping alone, bone pains, hypnagogic myoclonias, rhythmic movement disorder, enuresis, nocturia, confusion when awoken at night, nightmares, bodily movements during sleep, interrupted sleep, daytime sleepiness and daytime headache or stomach ache. Somnambulism was associated with rhythmic movement disorder, somniloquy, spontaneous confused arousals, nocturia and confusion when awoken at night. Increased risk of daytime sleepiness was found among children with fear of sleeping alone, onset insomnia, rhythmic movement disorder, spontaneous confused arousals, snoring, confusion when awoken, nightmares, bodily movements during sleep and headache or stomach ache.

Does age potentiate the smoking-related risk of fetal growth retardation?

Whether smoking is more harmful in certain pregnancies than others is a matter of controversy. In a large prospective study, interactions between smoking and other risk factors for small-for-gestational-age (SGA) were studied. Practically all Swedish live births between 1983 and 1985 were included, 280,809 births in all. In single births, significant interaction between maternal age on one hand and moderate (1-9 cigarettes/day) or heavy (ten cigarettes or more per day) smoking on the other, were obtained. The relative risk of SGA for heavy smokers versus non-smokers was 1.9 in the lowest age group (15-19 years) and 3.4 among women aged 40-44. Although smoking was twice as common among teenagers as compared to women aged 40-44, the attributable risk of smoking for SGA was higher among the older women. No other significant interactions with regard to fetal growth were obtained. In Sweden, there has been a shift towards delayed childbearing, and smoking during pregnancy is prevalent. These socio-demographic changes and the increased risk for SGA among older smokers must be considered when evaluating antenatal programs aimed at surveillance of fetal well-being.

Smoking habits in early pregnancy

In a prospective study, 2051 women were interviewed in early pregnancy regarding their own smoking habits as well as smoking habits among closely related persons. Fifty-five percent of the women had at one time or another been daily smokers. Of the 673 women (33%) smoking at the time of conception, 150 had quit smoking at the time of the interview (6 to 10 weeks later). Continued smoking was more common among women, whose parents had been smokers and among those whose husbands were smokers. Continued smoking was also more common among heavy smoking women (greater than 10 cigarettes per day), women who started to smoke at an early age and among women with previous births.

Smoking behaviour among pregnant women prior to antenatal care registration.

Changes in smoking behaviour during early pregnancy and factors influencing such changes were studied in an unselected, area-based population. During 1987, all women registered at the antenatal care clinics in Uppsala county. Sweden, received a self-administered questionnaire regarding past and present smoking habits. Thirty-two per cent (n = 1160) were daily smokers at the time of conception. Almost one-fourth of the smokers (n = 263) had quit smoking at the first visit to antenatal care 6-10 weeks later. Using logistic regression analyses, we found that low education, not living with infantss father and whether others smoked at home or at work were factors that were independently associated with increased risks of smoking at time of conception as well as continued smoking in early pregnancy. Continued smoking was also significantly more common among women with previous births, women who started smoking at an early age and women who smoked heavily.

Premature Rupture of the Membranes – Intervention or Not

Premature rupture of the membranes (PROM) in otherwise uncomplicated full-term single pregnancies was studied in a prospective randomized study. Ninety-three women were randomized to either induction with oxytocin infusion (n = 43) or expectant management (n = 50). Twenty-four and 26 respectively were nulliparas. In the induction group, all but 3 were delivered within 24 h from PROM. There were 3 vacuum extractions (VE), all in nulliparous women. No cesarean section (CS) was performed. In the expectancy group, 23 of 50 were delivered within 24 h. There were 5 VE and 3 CS in nulliparas and 1 VE and 1 CS in paras. The instrumental actions were mainly due to arrest of 1st or 2nd stage labor. The only clinical infections occurred in nulliparas in the expectancy group. Our conclusion is that parous women with PROM can be treated by either induction or expectancy while in nulliparas, induction after some hours expectation seems preferable.

The use of obstetric analgesia in Sweden 1983–1986

Summary. The use of obstetric analgesia was investigated in a Swedish population‐based prospective study of 335 207 births, which represents almost all women who had vaginal deliveries in Sweden between 1983 and 1986. Lumbar epidural analgesia (EDA) was used in 16%, paracervical block (PCB) in 12%, pethidinc or morphine in 49% and pudendal block in 62%. All four types of analgesia were much more commonly used by nulliparae than multiparae. Variables such as maternal age, smoking, nationality, relationship with the infants father and gestational age had only moderate influence on the rates of different types of analgesia. EDA and PCB were more frequently used in larger than in smaller hospitals and in the daytime than at night. No such differences were found for pethidine or morphine, or pudendal block, which were administered routinely by midwives.