Sari Räisänen

Contribution of risk factors to extremely, very and moderately preterm births - register-based analysis of 1,390,742 singleton births.

Background Preterm birth, defined as birth occurring before 37 weeks gestation, is one of the most significant contributors to neonatal mortality and morbidity, with long-term adverse consequences for health, and cognitive outcome. Objective The aim of the present study was to identify risk factors of preterm birth (≤36+6 weeks gestation) among singleton births and to quantify the contribution of risk factors to socioeconomic disparities in preterm birth. Methods A retrospective population–based case-control study using data derived from the Finnish Medical Birth Register. A total population of singleton births in Finland from 1987−2010 (n = 1,390,742) was reviewed. Results Among all singleton births (n = 1,390,742), 4.6% (n = 63,340) were preterm (<37 weeks), of which 0.3% (n = 4,452) were classed as extremely preterm, 0.4% (n = 6,213) very preterm and 3.8% (n = 54,177) moderately preterm. Smoking alone explained up to 33% of the variation in extremely, very and moderately preterm birth incidence between high and the low socioeconomic status (SES) groups. Reproductive risk factors (placental abruption, placenta previa, major congenital anomaly, amniocentesis, chorionic villus biopsy, anemia, stillbirth, small for gestational age (SGA) and fetal sex) altogether explained 7.7−25.0% of the variation in preterm birth between SES groups. Conclusions Smoking explained about one third of the variation in preterm birth groups between SES groups whereas the contribution of reproductive risk factors including placental abruption, placenta previa, major congenital anomaly, amniocentesis, chorionic villus biopsy, anemia, stillbirth, SGA and fetal sex was up to one fourth.

Lateral episiotomy protects primiparous but not multiparous women from obstetric anal sphincter rupture.

Objective. To identify the risk factors for obstetric anal sphincter rupture (OASR). Design and setting. Retrospective population‐based register study. Population. A total of 514,741 women with singleton pregnancy and vaginal delivery between 1997 and 2007 in Finland. Methods. Primiparous (n = 2,315) and multiparous women (n = 534) with OASR were compared with primiparous and multiparous women without OASR by using stepwise logistic regression analysis. Main outcome measure. The OASR risk. Results. Episiotomy decreased the likelihood of OASR for the primiparous [odds ratio (OR) 0.83, 95% CI (confidence interval) 0.75–0.92], but not the multiparous women (OR 2.01, 95% CI 1.67–2.44). The strongest risk factors for OASR among the primiparous women were forceps delivery (OR 10.20, 95% CI 3.60–28.90), birth weight over 4,000 g (OR 4.66, 95% CI 3.86–5.63), vacuum assisted delivery (OR 3.88, 95% CI 3.25–4.63), occiput posterior presentation (OR 3.17, 95% CI 1.64–6.15), and prolonged active second stage of birth (OR 2.06, 95% CI 1.65–2.58). Episiotomy was associated with decreased risks for OASR in vacuum assisted deliveries (OR 0.70, 95% CI 0.57–0.85). Risk factors for OASR among the multiparous women included forceps delivery (OR 10.13, 95% CI 2.46–41.81), prolonged active second stage of the birth (OR 7.18, 95% CI 4.32–11.91), birth weight over 4,000 g (OR 5.84, 95% CI 3.40–10.02), and vacuum assisted delivery (OR 4.17, 95% CI 3.17–5.48). Conclusions. The results support the restrictive use of episiotomy, since 909 episiotomies appear to be needed to prevent one OASR among primiparous women. Equivalent estimate in vacuum assisted deliveries among primiparous women was 66, favoring routine use of episiotomy in such cases.

Fear of childbirth predicts postpartum depression: A population-based analysis of 511 422 singleton births in Finland

Objectives To study how reproductive risks and perinatal outcomes are associated with postpartum depression treated in specialised healthcare defined according to the International Classification of Diseases (ICD)-10 codes, separately among women with and without a history of depression. Design A retrospective population-based case–control study. Setting Data gathered from three national health registers for the years 2002−2010. Participants All singleton births (n=511 422) in Finland. Primary outcome measures Prevalence of postpartum depression and the risk factors associated with it. Results In total, 0.3% (1438 of 511 422) of women experienced postpartum depression, the prevalence being 0.1% (431 of 511 422) in women without and 5.3% (1007 of 18 888) in women with a history of depression. After adjustment for possible covariates, a history of depression was found to be the strongest risk factor for postpartum depression. Other strong predisposing factors for postpartum depression were fear of childbirth, caesarean birth, nulliparity and major congenital anomaly. Specifically, among the 30% of women with postpartum depression but without a history of depression, postpartum depression was shown to be associated with fear of childbirth (adjusted OR (aOR 2.71, 95% CI 1.98 to 3.71), caesarean birth (aOR 1.38, 95% CI 1.08 to 1.77), preterm birth (aOR 1.65, 95% CI 1.08 to 2.56) and major congenital anomaly (aOR 1.67, 95% CI 1.15 to 2.42), compared with women with no postpartum depression and no history of depression. Conclusions A history of depression was found to be the most important predisposing factor of postpartum depression. Women without previous episodes of depression were at an increased risk of postpartum depression if adverse events occurred during the course of pregnancy, especially if they showed physician-diagnosed fear of childbirth.

The Burden of Childhood Asthma and Late Preterm and Early Term Births

OBJECTIVE To evaluate the association between gestational age at birth and the risk of subsequent development of asthma. STUDY DESIGN We conducted a retrospective observational hospital-based birth case-control study in a university-based obstetrics and gynecology department in Finland. A total of 44,173 women delivering between 1989 and 2008 were linked with the social insurance register to identify asthma reimbursements for their offspring (n = 2661). Pregnancy factors were recorded during pregnancy. Infants were categorized as moderately preterm (≤ 32 weeks), late preterm (33-36 weeks), early term (37-38 weeks), term (39-40 weeks), or late term and postterm (≥ 41 weeks). The main outcome measure was asthma among the infants. RESULTS Children born moderately preterm (≤ 32 weeks gestation) had a significantly increased risk of asthma (aOR, 3.9; 95% CI, 3.2-4.8). The risk of asthma was also increased in those born late preterm (aOR, 1.7; 95% CI, 1.4-2.0) and early term (aOR, 1.2; 95% CI, 1.1-1.4). In contrast, delivery at 41 weeks or later seemed to decrease the risk of asthma (aOR, 0.9; 95% CI, 0.8-1.0). The burden of asthma associated with preterm birth was associated mainly with early term infants, in whom 108 extra cases of asthma were observed. CONCLUSION Even though the individual risk of asthma was inversely correlated with gestational age at birth, the overall burden brought about by delivery before term was associated with late preterm and early term deliveries. Furthermore, delivery after term was protective against asthma.

Risk factors for and perinatal outcomes of major depression during pregnancy: a population-based analysis during 2002-2010 in Finland

Objectives To identify risk factors for and the consequences (several adverse perinatal outcomes) of physician-diagnosed major depression during pregnancy treated in specialised healthcare. Design A population-based cross-sectional study. Setting Data were gathered from Finnish health registers for 1996–2010. Participants All singleton births (n=511 938) for 2002–2010 in Finland. Primary outcome measures Prevalence, risk factors and consequences of major depression during pregnancy. Results Among 511 938 women, 0.8% experienced major depression during pregnancy, of which 46.9% had a history of depression prior to pregnancy. After history of depression, the second strongest associated factor for major depression was fear of childbirth, with a 2.6-fold (adjusted OR (aOR=2.63, 95% CI 2.39 to 2.89) increased prevalence. The risk profile of major depression also included adolescent or advanced maternal age, low or unspecified socioeconomic status (SES), single marital status, smoking, prior pregnancy terminations, anaemia and gestational diabetes regardless of a history of depression. Outcomes of pregnancies were worse among women with major depression than without. The contribution of smoking was substantial to modest for small-for-gestational age newborn (<−2 SD below mean birth), low birth weight (<2500 g), preterm birth (<37 weeks) and admission to neonatal intensive care associated with major depression, whereas SES made only a minor contribution. Conclusions Physician-diagnosed major depression during pregnancy was found to be rare. The strongest risk factor was history of depression prior to pregnancy. Other associated factors were fear of childbirth, low SES, lack of social support and unhealthy reproductive behaviour such as smoking. Outcomes of pregnancies were worse among women with major depression than without. Smoking during pregnancy made a substantial to modest contribution to adverse outcomes associated with depression during pregnancy.

Fear of childbirth in nulliparous and multiparous women: a population-based analysis of all singleton births in Finland in 1997-2010

To identify risk factors for fear of childbirth (FOC) according to parity and socioeconomic status, and to evaluate associations between FOC and adverse perinatal outcomes.

Smoking cessation in the first trimester reduces most obstetric risks, but not the risks of major congenital anomalies and admission to neonatal care: a population-based cohort study of 1 164 953 singleton pregnancies in Finland

Background In industrialised countries, approximately 5–20% of women smoke during pregnancy. We aim to study the association between smoking during pregnancy and adverse perinatal outcomes. Methods A retrospective population–based cohort study using data on all singleton births between 1991 and 2010 (n=1 164 953) derived from the Finnish Medical Birth Register. Results Of all the mothers included, 82.3% were non-smokers, 2.6% quit smoking during the first trimester of pregnancy, 12.5% smoked throughout pregnancy and 2.7% had no information on smoking. Continuing smoking after the first trimester of the pregnancy was associated with an increased prevalence of admission to a neonatal intensive care unit, stillbirth, preterm birth (<37 gestational weeks), low birth weight (LBW, <2500 g), small for gestational age (SGA, <−2 SDs) and major congenital anomaly compared with non-smokers. Smoking cessation reduced the risk of prematurity, stillbirth, LBW and SGA close to or at similar levels as those of non-smokers. Tobacco exposure in early pregnancy resulted in a 19% increased prevalence of admission to neonatal intensive care unit and a 22% increased prevalence of major congenital anomaly compared with non-smokers. Conclusions Smoking cessation appeared to reduce pregnancy risks close to those of non-smoking peers. Exposure to early pregnancy smoking was, however, associated with an increased admission to neonatal intensive care and an increased prevalence of major congenital anomalies.

The increased incidence of obstetric anal sphincter rupture--an emerging trend in Finland.

OBJECTIVE To describe recent trends in the prevalence and risk factors of obstetric anal sphincter ruptures during between 1997 and 2007 in Finland. METHOD We analyzed a population-based register of 514,741 women with singleton vaginal deliveries recorded in the Finnish Medical Birth Register. Primiparous (n=2315) and multiparous women (n=534) with anal rupture compared in terms of possible risk factors to primiparous (n=215,463) and multiparous (n=296,429) women without anal rupture, respectively, using stepwise logistic regression analysis. RESULTS The occurrence of anal rupture increased from 0.5% in 1997-1999 to 1.8% in 2006-2007 among primiparous women, and from 0.1% in 1997-2001 to 0.3% in 2006-2007 among multiparous women. Over the study period, the likelihood of women having anal rupture in these groups increased by a factor of 3.28 (95% CI 2.86-3.76) and 2.83 (95% CI 2.19-3.67), respectively, after adjustments for strong associations with many known risks. Changes in population characteristics and in the use of interventions were small, and these did not cause the increased anal rupture rate. The only exception was vacuum-assisted deliveries, which explained about 9% of the rising anal rupture risk. CONCLUSIONS The current obstetric practice is not optimal for protecting the perineum and reflects the need to standardise obstetric care.

High episiotomy rate protects from obstetric anal sphincter ruptures: A birth register-study on delivery intervention policies in Finland

Aim: To assess the impact of hospital episiotomy policy on obstetric and anal sphincter rupture (OASR, n = 2448) rates and risks among singleton vaginal deliveries in Finland between 1997 and 2007. Methods: An observational, retrospective, population-based register study. All 424,297 women in hospitals with more than 1000 deliveries annually, were divided into three groups based on the episiotomy rate quartiles for 11 years and separated on the basis of whether the women were primiparous or multiparous. The lowest and the highest quartiles were compared against the hospitals with intermediate episiotomy rates, comprising the two quartiles around the median. Stepwise logistic regression analysis was used to adjust significant risk factors. Results: The annual range of episiotomy varied from 11 to 94% in primiparous women, and from 1 to 46% in multiparous women. After adjustment the risk of OASR appears to be 39% lower (OR 0.61, 95% CI 0.52—0.90) in primiparous and 45% lower (OR 0.55, 95% CI 0.42—0.72) in multiparous women delivered in the highest quartile hospitals. At an individual level, episiotomy was a protective factor (OR 0.82, 95% CI 0.75—0.91) in primiparous women, but increased the risk by 2.36-fold in multiparous women (OR 2.36, 95% CI 1.86—2.84). Conclusions: The results suggest that high episiotomy rate provided protection from OASR among both groups of women. Among the multiparous women, the 2.4-fold risk of OASR related to episiotomy at an individual level might be explained by confounding by indication, since episiotomy was performed more often to women at a high risk of OASR.

Need for and consequences of episiotomy in vaginal birth: a critical approach

OBJECTIVE to describe and explain the short-term effects of lateral episiotomy, and determine the factors associated with more/less common use of episiotomy. DESIGN prospective cross-sectional survey using a postal questionnaire. SETTING the study was conducted at two university hospitals and one regional hospital in Finland between October and December 2006. The hospitals were chosen using cluster sampling. The sample consisted of 1000 vaginal births, and data were collected using questionnaires which were completed by midwives or student midwives. The overall response rate was 88%. PARTICIPANTS midwives or student midwives who took care of the women in labour provided information about childbearing women (n=879), obstetric factors and details of staff experience. FINDINGS episiotomies were more common among primiparous than multiparous women (55% vs 12%, p0.001). More common use of episiotomy was also associated with induced births compared with spontaneous births in primiparous women (66% vs 53%, p=0.036), assisted vaginal births in all women (89% vs 25%, p0.001), and a prolonged active second stage of labour and epidural analgesia (17% vs 10%, p=0.036) in multiparous women. Correspondingly, episiotomies were less common among primiparous (44% vs 57%, p=0.041) and multiparous (7% vs 16%, p=0.003) women using spontaneous pushing compared with coached pushing. In the active second stage of labour, alternative birth positions (lateral, squatting, all fours, sitting) were associated with less common use of episiotomy than half-sitting or lithotomy positions among primiparous women (22% vs 48% vs 85%, p0.001). There were no differences between primiparous women with and without episiotomy in low Apgar score at 1minute (10.6% vs 6.4%, p=0.131) or 5minutes (1.8% vs 1.1%, p=0.557), or between multiparous women with and without episiotomy in low Apgar score at 1minute (1.9% vs 2.2%, p=0.855) or 5minutes (0% vs 0.5%, p=0.603). There were more first- and second-degree perineal injuries as well as injuries to the vagina, labia minora and urethra in births performed without episiotomies among primiparous women (p0.001). Correspondingly, third-degree perineal injuries were more common if episiotomy was performed in both primiparous (2.2% vs 1.6%) and multiparous women (3.7% vs 0%). The maternity hospital was the most significant determinant of the episiotomy rate (odds ratio 1 vs 1.9 vs 2.6, p=0.049). KEY CONCLUSIONS episiotomy rates can be reduced without causing harm to women or newborn babies. Episiotomies can be avoided if induction and vacuum assistance are used sparingly, and if spontaneous pushing techniques and alternative birth positions (lateral, sitting, squatting, all fours) are used more often during labour.