Cleft Laterality Dental Arch Relationship Outcomes for Children with Unilateral Cleft Lip and Palate in New Zealand

OBJECTIVES

To investigate cleft laterality dental arch relationship outcomes of children with non-syndromic complete unilateral cleft lip and palate (UCLP) in New Zealand.

DESIGN

A retrospective nationwide study.

SETTINGS

Virtual 3D orthodontic study models collected prior to undertaking secondary alveolar bone grafting.

PARTICIPANTS

A total of 104 patients with UCLP (L = 80: R = 24).

OUTCOME MEASURES

Four calibrated assessors used the GOSLON Yardstick and 100 mm Visual Analogue Scale (VAS) to score the randomised models on 2 separate assessment sessions. Weighted Kappa were used to determine the intra/inter-rater reliability for the GOSLON and correlations for the VAS.

RESULTS

Intra-rater reliability ranged from 0.57-0.88 (GOSLON) and 0.45-0.93 (VAS). Inter-rater reliability ranged from 0.62-0.86 (GOSLON) and 0.64-0.93 (VAS).GOSLON scores for the left UCLP were 31.2% for good/very good; 26.3% for fair; 42.5% for poor/very poor while the right UCLP scored 8.3% for good/very good; 37.5% for fair; 54.2% for poor/very poor. The mean VAS for left and right UCLP were 53.4 (sd 22.5) and 44.6 (sd 17.1) respectively. Neither the GOSLON nor VAS differences reached statistical significance (both P = .08).

CONCLUSIONS

From a clinical perspective right UCLP had worse dental arch relationship outcomes, however, these differences failed to reach statistical significance. Further studies using larger sample sizes are required to determine if cleft laterality is an important consideration when investigating UCLP dental arch outcomes.

Risk factors for late preterm and term stillbirth: A secondary analysis of an individual participant data meta-analysis

OBJECTIVE

Identify independent and novel risk factors for late-preterm (28-36 weeks) and term (≥37 weeks) stillbirth and explore development of a risk-prediction model.

DESIGN

Secondary analysis of an Individual Participant Data (IPD) meta-analysis investigating modifiable stillbirth risk factors.

SETTING

An IPD database from five case-control studies in New Zealand, Australia, the UK and an international online study.

POPULATION

Women with late-stillbirth (cases, n = 851), and ongoing singleton pregnancies from 28 weeks' gestation (controls, n = 2257).

METHODS

Established and novel risk factors for late-preterm and term stillbirth underwent univariable and multivariable logistic regression modelling with multiple sensitivity analyses. Variables included maternal age, body mass index (BMI), parity, mental health, cigarette smoking, second-hand smoking, antenatal-care utilisation, and detailed fetal movement and sleep variables.

MAIN OUTCOME MEASURES

Independent risk factors with adjusted odds ratios (aOR) for late-preterm and term stillbirth.

RESULTS

After model building, 575 late-stillbirth cases and 1541 controls from three contributing case-control studies were included. Risk factor estimates from separate multivariable models of late-preterm and term stillbirth were compared. As these were similar, the final model combined all late-stillbirths. The single multivariable model confirmed established demographic risk factors, but additionally showed that fetal movement changes had both increased (decreased frequency) and reduced (hiccoughs, increasing strength, frequency or vigorous fetal movements) aOR of stillbirth. Poor antenatal-care utilisation increased risk while more-than-adequate care was protective. The area-under-the-curve was 0.84 (95% CI 0.82-0.86).

CONCLUSIONS

Similarities in risk factors for late-preterm and term stillbirth suggest the same approach for risk-assessment can be applied. Detailed fetal movement assessment and inclusion of antenatal-care utilisation could be valuable in late-stillbirth risk assessment.

Smoking in pregnancy is a key factor for sudden infant death among Māori

AIM

To examine the sudden unexpected death in infancy (SUDI) disparity between Māori and non-Māori in New Zealand.

METHODS

A nationwide prospective case-control study ran from March 2012 to February 2015. Exposure to established SUDI risk factors was analysed to investigate the disparity experienced by Māori. Infant ethnicity was based on mother's ethnicity. Māori ethnicity was prioritised. Non-Māori includes Pacific, Asian, NZ European and Other.

RESULTS

There were 137 cases and 649 controls. The Māori SUDI rate was 1.41/1000 live births compared to 0.53/1000 for non-Māori. Parents/caregivers of 132 cases (96%) and 258 controls (40%) were interviewed. Smoking in pregnancy was associated with an equally increased SUDI risk for Māori (adjusted OR = 8.11, 95% CI = 2.64, 24.93) and non-Māori (aOR = 5.09, 95% CI = 1.79, 14.47), as was bed-sharing (aOR = 3.66, 95% CI = 1.49, 9.00 vs aOR = 11.20, 95% CI = 3.46, 36.29). Bed-sharing prevalence was similar; however, more Māori controls smoked during pregnancy (46.7%) than non-Māori (22.8%). The main contributor relating to increased SUDI risk for Māori/non-Māori infants is the combination of smoking in pregnancy and bed sharing.

CONCLUSION

The association between known SUDI risk factors, including bed sharing and/or smoking in pregnancy and SUDI risk, is the same regardless of ethnicity. Māori infants are exposed more frequently to both behaviours because of the higher Māori smoking rate.

The role for cyclic Glycine-Proline, a biological regulator of insulin-like growth factor-1 in pregnancy-related obesity and weight changes

Cyclic Glycine-Proline (cGP) regulates the homeostasis of insulin-like growth factor (IGF)-1 function and cGP/IGF-1 ratio determines IGF-1 bioactivity in vitro and in vivo. Plasma IGF-1 represents largely inactive IGF-1 and weakly associated with human obesity and hypertension. We evaluated the regulatory role for cGP in pregnancy-related obesity and hypertension, and in obesity status between pregnancy and postpartum. Women were recruited in their first pregnancy. A cross-sectional study compared plasma concentration of cGP, IGF-1 and IGF binding protein (IGFBP)-3 in women with obesity and/or hypertension to normal controls 6-year postpartum using UPLC-MS and ELISA. A longitudinal study compared the changes of these peptides from 15-week gestation to 6-year post-partum in the women who remained normal weight, remained obese or changed to obese or to normal respectively. Study 1 is a cross-sectional study. The obese group had lower IGF-1(p = 0.001), higher cGP/IGF-1 ratio (p = 0.0055) and the hypertensive group had lower IGFBP-3 (p = 0.046) and cGP (p = 0.043) than the controls. Study 2 is a longitudinal study. Women with weight loss had increased cGP/IGF-1 ratio (p = 0.0026) and decreased IGFBP-3 (p = 0.0001) compared with women whose weight remained normal. Women with weight gain had lower IGFBP-3 (p less than 0.0001) only. Women who remained obese had increased cGP/IGF-1 ratio (p = 0.006) only. Increase in cGP/IGF-1 ratio is associated with obesity, but not hypertension. Changes of IGFBP-3 and/or cGP/IGF-1 ratio are associated with weight changes. The data suggest the role for cGP in obesity through autocrine regulation of IGF-1.

Effect of Lactobacillus rhamnosus HN001 in Pregnancy on Postpartum Symptoms of Depression and Anxiety: A Randomised Double-blind Placebo-controlled Trial

Background

Probiotics may help to prevent symptoms of anxiety and depression through several putative mechanisms.

Objective

The aim of this study was to evaluate the effect of Lactobacillus rhamnosus HN001 (HN001) given in pregnancy and postpartum on symptoms of maternal depression and anxiety in the postpartum period. This was a secondary outcome, the primary outcome being eczema in the offspring at 12 months of age.

Design, Setting, Participants

A randomised, double-blind, placebo-controlled trial of the effect of HN001 on postnatal mood was conducted in 423 women in Auckland and Wellington, New Zealand. Women were recruited at 14–16 weeks gestation.

Intervention

Women were randomised to receive either placebo or HN001 daily from enrolment until 6 months postpartum if breastfeeding.

Outcome Measures

Modified versions of the Edinburgh Postnatal Depression Scale and State Trait Anxiety Inventory were used to assess symptoms of depression and anxiety postpartum.

Trial Registration

Australia NZ Clinical Trials Registry: ACTRN12612000196842.

Findings

423 women were recruited between December 2012 and November 2014. 212 women were randomised to HN001 and 211 to placebo. 380 women (89.8%) completed the questionnaire on psychological outcomes, 193 (91.0%) in the treatment group and 187 (88.6%) in the placebo group. Mothers in the probiotic treatment group reported significantly lower depression scores (HN001 mean = 7·7 (SD = 5·4), placebo 9·0 (6·0); effect size -1·2, (95% CI -2·3, -0·1), p = 0·037) and anxiety scores (HN001 12·0 (4·0), placebo 13·0 (4·0); effect size -1·0 (-1·9, -0·2), p = 0·014) than those in the placebo group. Rates of clinically relevant anxiety on screening (score > 15) were significantly lower in the HN001 treated mothers (OR = 0·44 (0·26, 0·73), p = 0·002).

Interpretation

Women who received HN001 had significantly lower depression and anxiety scores in the postpartum period. This probiotic may be useful for the prevention or treatment of symptoms of depression and anxiety postpartum.

Funding Source

Health Research Council of New Zealand (11/318) and Fonterra Co-operative Group Ltd.

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The microbiome-gut-brain axis may be important for mental health.

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We conducted a study of probiotic supplementation in pregnancy and 6 months after delivery if breastfeeding.

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The probiotic treatment group reported significantly lower depression and anxiety scores than those in the placebo group.

There is mounting evidence from animal studies that the microbiome-gut-brain axis may be important for mental health. Depression and anxiety in pregnancy and after birth affects 10–15% of women, although many are not recognised or treated. We conducted a double-blind placebo-controlled study of probiotic (Lactobacillus rhamnosus HN001) supplementation (from early pregnancy through to 6 months after delivery if breastfeeding) on postnatal symptoms of depression and anxiety in a group (n = 380) of healthy women. Mothers in the probiotic treatment group reported significantly lower depression and anxiety scores than those in the placebo group.

Falling asleep: the determinants of sleep latency

BACKGROUND

Difficulty falling asleep (prolonged sleep latency) is a frequently reported problem in school-aged children.

AIMS

This study aimed to describe the distribution of sleep latency and factors that influence its duration.

METHODS

871 children of European mothers were recruited at birth. 591 (67.9%) children took part in the follow-up at 7 years of age. Sleep and daytime activity were measured objectively by an actigraph worn for 24 h.

RESULTS

Complete sleep data were available for 519 children (87.8%) with a mean age of 7.3 years (SD 0.2). Median sleep latency was 26 minutes (interquartile range 13-42). Higher mean daytime activity counts were associated with a decrease in sleep latency (-1.2 minutes per 102 movement count per minute, p = 0.05). Time spent in sedentary activity was associated with an increase in sleep latency (3.1 minutes per hour of sedentary activity, p = 0.01).

CONCLUSIONS

These findings emphasise the importance of physical activity for children, not only for fitness, cardiovascular health and weight control, but also for promoting good sleep.

Risk factors for asthma at 3.5 and 7 years of age

BACKGROUND

It has been suggested that factors in early life including exposure to allergens and microbes may influence the development of asthma.

OBJECTIVE

To identify risk factors for asthma in early childhood. Methods Eight-hundred and seventy-one children of European mothers were enrolled at birth, of whom 385 (44.2%) were born small for gestational age (SGA) and 486 were appropriate for gestational age (AGA). Data were collected at birth, 12 months, 3.5 years of age (y) and 7 y. The outcome of interest (current wheeze) was defined as a positive response to the question: 'Has your child had wheezing or whistling in the chest in the last 12 months?'

RESULTS

Participation rate was 85.4% at 1 y, 63.1% at 3.5 y and 68.0% at 7 y. The prevalence of asthma was 23.8% at 3.5 y and 18.1% at 7 y. Antibiotic use in the first year of life and day care in the first year of life were associated with increased risk of wheeze at 7 y [odds ratio (OR)=4.3 95% confidence interval (CI) (1.8-10.1) and OR=2.8 95% CI (1.2-6.5), respectively], but not at 3.5 y. Exposure to dogs was a risk factor for asthma at both ages [OR=2.1 95% CI (1.1-3.8)] as was sleeping on a used cot mattress in the first year of life [OR=1.8 95% CI (1.0-3.2)].

CONCLUSIONS

There was a significant association between antibiotic use and day care in the first year of life and wheezing at 7 y but not at 3.5 y. This strengthens the argument that these factors increase the risk of asthma. We have also made the novel observation that sleeping on a used mattress in the first year of life is a risk factor for wheezing at 3.5 and 7 y. Capsule summary This prospective study of 871 children made the novel observation that sleeping on a used mattress in the first year of life was a risk factor for wheezing at 3.5 and 7 y.

Placenta weight percentile curves for singleton deliveries

OBJECTIVE

To produce population-based, gender- and gestational-age-specific centile curves for placental weight.

DESIGN

Population study.

SETTING

Medical Birth Registry of Norway.

POPULATION

All singleton live births in Norway from 1 January 1999 to 31 December 2002.

METHODS

In a cohort of children born in Norway, placental weights and the ratio of the birthweight to the placental weight were analysed to produce percentile curves.

MAIN OUTCOME MEASURES

Placental weight, birthweight-to-placental weight ratio.

RESULTS

Tables and figures are presented for placental percentiles curves according to gestational age and gender. Also, tables and figures are presented for the ratio of birthweight to placental weight. CONCLUSIONS To our knowledge, this is the first time that population percentile curves have been produced for placental weights and hence for the ratio of birthweight to placental weight. These percentile curves may act as a reference for other populations as well until population-specific curves can be produced.

Are the risk factors for SIDS different for preterm and term infants?

BACKGROUND

Mortality from SIDS has declined since the recommendation that infants are not placed prone to sleep. SIDS mortality is higher in infants born preterm than those born at term.

AIM

To determine if risk factors for SIDS are any different for preterm and term infants.

METHODS

Mortality data over time were used to determine whether the reduction in SIDS mortality rates had occurred equally in term and preterm infants. Data from two New Zealand studies (a case-control study and a case-cohort study) were used to determine if any differences existed in risk factors for SIDS between term and preterm infants before and after the SIDS prevention campaign.

RESULTS

SIDS mortality appears to have decreased by similar proportions in term and preterm infants. Risk factors for SIDS were similar in preterm and term infants, except for parity where there was a significant interaction. Increasing parity was a risk factor for SIDS in term infants but not preterm infants.

CONCLUSION

SIDS rates have decreased at comparable rates in term and preterm infants, but preterm birth still remains a risk factor for SIDS. The magnitude of the odds ratios associated with modifiable risk factors were similar for both groups. There may however be a difference in risk associated with parity between term and preterm infants. The messages for risk factors for SIDS are applicable to mothers of preterm as well as term infants.

Maternal stress, social support and preschool children's intelligence

BACKGROUND

Despite some research suggesting maternal stress may be associated with cognitive impairment in preschool children, there has been little direct investigation of the association between maternal stress, social support and children's intelligence.

AIM

To determine whether maternal stress and social support during pregnancy and during the child's early years of life are associated with the intelligence test performance of preschool children.

STUDY DESIGN

Five hundred and fifty European mothers and children enrolled in the Auckland Birthweight Collaborative Study at birth were interviewed when the child was 3 1/2 years of age.

SUBJECTS

All children were full term gestation and approximately half the sample were small for gestational age at birth (SGA = birthweight < or = 10th percentile).

OUTCOME MEASURE

The cognitive ability of children aged 3 1/2 years was assessed using the Stanford Binet Intelligence Scale 4th Edition.

RESULTS

In the total sample, maternal stress and lack of social support during pregnancy were significantly associated with lower intelligence test scores of children. In the group of SGA children, maternal stress post pregnancy was significantly associated with lower intelligence test scores in children. There is evidence that for some children the presence of good social support for mothers may reduce the negative effects of maternal stress on children's cognitive development.

CONCLUSION

Maternal stress and lack of social support appear to be associated with lower intelligence test scores of preschool children. Social support may attenuate some of the negative effects of maternal stress on intelligence in children born small for gestational age.

Milk versus medicine for the treatment of iron deficiency anaemia in hospitalised infants

AIMS

To compare iron fortified follow-on milk (iron follow-on), iron fortified partially modified cows' milk (iron milk), and iron medicine for the treatment of iron deficiency anaemia (IDA) in hospitalised infants.

METHODS

In a randomised controlled trial, infants aged 9-23 months with IDA and who were hospitalised with an acute illness received iron follow-on (12 mg/l ferrous iron), iron milk (12.9 mg/l ferrous iron), or iron medicine (ferrous gluconate at 3 mg/kg of elemental iron once daily). All interventions were given for three months. Changes in measures of iron status three months after hospital discharge were determined.

RESULTS

A total of 234 infants were randomised. Iron status was measured at follow up in 59 (70%) iron medicine, 49 (66%) iron follow-on, and 54 (70%) iron milk treated infants. There was a significant (mean, 95% CI) increase in haemoglobin (15 g/l, 13 to 16) and iron saturation (9%, 8 to 10) and decrease in ferritin (-53 microg/l, -74 to -31) in all three groups. Mean cell volume increased in iron follow-on (2 fl, 1 to 3) and iron milk (1 fl, 0.1 to 3) treated infants, but not in the iron medicine group (1 fl, -1 to 2). The proportion with IDA decreased in all three groups: iron medicine 93% to 7%, iron follow-on 83% to 8%, and iron milk 96% to 30%. Adverse effects, primarily gastrointestinal, occurred in 23% of the iron medicine, 14% of the iron follow-on, and 13% of the iron milk group.

CONCLUSIONS

Iron fortified follow-on milk, iron fortified partially modified cows' milk, and iron medicine all effectively treat IDA in infancy.

Risk factors for atopic dermatitis in New Zealand children at 3.5 years of age

BACKGROUND

The prevalence of atopic dermatitis (AD) is increasing in Western societies. The hygiene hypothesis proposes that this is due to reduced exposure to environmental allergens and infections during early life.

OBJECTIVES

To examine factors associated with a diagnosis of AD at 3.5 years of age, especially those factors implicated by the hygiene hypothesis.

METHODS

The Auckland Birthweight Collaborative study is a case-control study of risk factors for small for gestational age babies. Cases were born at term with birthweight < or = 10th centile; controls were appropriate for gestational age, with birthweight > 10th centile. The infants were assessed at birth, 1 year and 3.5 years of age. Data were collected by parental interview and examination of the child. AD was defined as the presence of an itchy rash in the past 12 months with three or more of the following: history of flexural involvement; history of generally dry skin; history of atopic disease in parents or siblings; and visible flexural dermatitis as per photographic protocol. Statistical analyses took into account the disproportionate sampling of the study population.

RESULTS

Analysis was restricted to European subjects. Eight hundred and seventy-one children were enrolled at birth, 744 (85.4%) participated at 1 year, and 550 (63.2%) at 3.5 years. AD was diagnosed in 87 (15.8%) children seen at 3.5 years. The prevalence of AD did not differ by birthweight. AD at 3.5 years was associated with raised serum IgE > 200 kU L(-1), and wheezing, asthma, rash or eczema at 1 year. In multivariate analysis, adjusted for parental atopy and breastfeeding, AD at 3.5 years was associated with atopic disease in the parents: maternal atopy only, adjusted odds ratio (OR) 3.83, 95% confidence interval (CI) 1.20-12.23; paternal atopy only, adjusted OR 3.59, 95% CI 1.09-11.75; both parents atopic, adjusted OR 6.12, 95% CI 2.02-18.50. There was a higher risk of AD with longer duration of breastfeeding: < 6 months, adjusted OR 6.13, 95% CI 1.45-25.86; > or = 6 months, adjusted OR 9.70, 95% CI 2.47-38.15 compared with never breastfed. These findings remained significant after adjusting for environmental factors and a personal history of atopy. AD at 3.5 years was associated with owning a cat at 3.5 years (adjusted OR 0.45, 95% CI 0.21-0.97) but not with owning a dog at 3.5 years, pets at 1 year, nor with older siblings. Furthermore, AD at 3.5 years was not associated with gender, socioeconomic status, maternal smoking, parity, damp, mould, immunizations, body mass index or antibiotic use in first year of life.

CONCLUSIONS

A personal and a parental history of atopic disease are risk factors for AD at 3.5 years. Duration of breastfeeding was associated with an increased risk of AD. No association was found with those factors implicated by the hygiene hypothesis. This study suggests that breastfeeding should not be recommended for the prevention of AD.

Breastfeeding and intelligence of preschool children

AIM

To investigate whether breastfeeding during infancy is a determinant of intelligence at 3.5 y.

METHODS

Five hundred and fifty European children enrolled at birth in the Auckland Birthweight Collaborative Study were assessed at 3.5 y of age. Approximately half were small for gestational age (SGA < or =10th percentile) at birth and half were appropriate for gestational age (AGA >10th percentile). Duration of breastfeeding was recorded at maternal interview, and the intelligence of children was assessed using the Stanford Binet Intelligence Scale. Regression analysis was used to calculate estimates of difference in intelligence scores between breastfeeding groups for the total sample and the group of SGA children. Analyses of the total sample were weighted to account for the disproportionate sampling of SGA children.

RESULTS

Breastfeeding was not significantly related to intelligence scores in the total sample despite a trend for longer periods of breastfeeding to be associated with higher intelligence scores. However, in the SGA group, breastfeeding was significantly related to IQ at 3.5 y. Small for gestational age children who were breastfed for longer than 12 mo had adjusted scores 6.0 points higher than those who were not breastfed (p=0.06).

CONCLUSION

Breastfeeding may be particularly important for the cognitive development of preschool children born small for gestational age.

Maternal nutritional risk factors for small for gestational age babies in a developed country: a case-control study

AIMS

To assess the effect of maternal diet during pregnancy on the risk of delivering a baby who is small for gestational age (SGA).

METHODS

Case-control study of 844 cases (SGA) and 870 controls (appropriate size for gestational age (AGA)). Only term (37+ completed weeks of gestation) infants were included. Retrospective food frequency questionnaires were completed at birth on the diet at the time of conception and in the last month of pregnancy.

RESULTS

At the time of conception, mothers of AGA infants ate significantly more servings of carbohydrate rich food and fruit, and were more likely to have taken folate and vitamin supplements than mothers of SGA infants. There was some evidence that mothers of AGA infants also ate more servings of dairy products, meat, and fish (0.05 < p < 0.1). However, after adjustment for maternal ethnicity, smoking, height, weight, hypertension, and occupation, fish intake (p = 0.04), carbohydrate-rich foods (p = 0.04), and folate supplementation (p = 0.02) were associated with a reduced risk of SGA. In the last month of pregnancy, only iron supplementation was associated with a reduced risk of SGA (p = 0.05) after adjustment for potential confounders.

CONCLUSIONS

This study suggests that small variations in maternal diets within the normal range during pregnancy in developed countries are associated with differences in birth weight.

Stress and lack of social support as risk factors for small-for-gestational-age birth

AIM

To determine the contributions of social support and perceived stress to the risk of small-for-gestational-age birth.

METHODS

The investigation was a case-control study of mothers of infants born at 37 or more completed weeks of gestation. Cases weighed less than the sex-specific 10th percentile for gestational age at birth (small for gestational age (SGA), n = 836), and controls (appropriate for gestational age (AGA), n = 870) comprised a random selection of heavier babies.

RESULTS

In univariate analyses measures of informal social support, but not perceived stress or formal social support, were associated with SGA birth. It was found that Asian mothers are less likely to receive support from families and friends. After adjustment for ethnicity, informal social support was not associated with SGA.

CONCLUSIONS

Support appears to reduce the risk of SGA births, but after adjustment for ethnicity this is no longer the case. Stress during pregnancy was not associated with SGA birth.

Snoring in the first year of life

AIM

To describe the prevalence of snoring in infancy and the factors associated with snoring.

METHODS

The investigation comprised a cross-sectional study of 1800 infants. Snoring was ascertained by interviewer-administered questionnaire.

RESULTS

The prevalence of snoring was 15.8% in the first 4 wk of life and 26.1% in the past 2 wk. Snoring in the past 2 wk was associated with increasing age of the infant, male gender, maternal smoking, sleep position, number of respiratory infections and snoring in the first 4 wk of life after adjustment for potential confounders. No associations were found with snoring in the first 4 wk of life.

CONCLUSION

Snoring is common in infancy. The identified risk factors for snoring are probably causally related to snoring. Further studies are needed to establish whether snoring in infancy is associated with current or subsequent morbidity.

Smoking, nicotine and tar and risk of small for gestational age babies

AIMS

To assess the effect of maternal smoking and environmental tobacco smoke (ETS) on risk of small for gestational age infants (SGA).

METHODS

Case-control study of 844 cases and 870 controls.

RESULTS

Maternal smoking in pregnancy was associated with an increased risk of SGA (adjusted odds ratio (OR)= 2.41; 95% confidence interval (CI) = 1.78, 3.28). We could not detect an increased risk of SGA with paternal smoking, or with other household smokers when the mother was a non-smoker, but did find an increased risk with exposure to ETS in the workplace or while socializing. Infants of mothers who ceased smoking during pregnancy were not at increased risk of SGA, but those who decreased but did not stop remained at risk of SGA. There was no evidence that the concentration of nicotine and tar in the cigarettes influenced the risk of SGA.

CONCLUSIONS

Maternal smoking in pregnancy is a major risk factor for SGA. This study suggests that mothers should be advised to cease smoking completely during pregnancy, and that a reduction in the number of cigarettes smoked or smoking low tar or nicotine concentration cigarettes does not reduce the risk of SGA.

Socioeconomic status and preterm birth: New Zealand trends, 1980 to 1999

BACKGROUND

While a number of countries have reported rising preterm birth rates over the past two decades, none has examined the effects of socioeconomic status on preterm birth at a national level.

AIM

To document the changing incidence of preterm birth in New Zealand over the past 20 years and to determine whether particular socioeconomic or ethnic subsections of the population have contributed disproportionately to the changes seen.

METHODS

Birth registration data routinely available from the New Zealand Health Information Service were analysed for the period 1980-99. Information for a total of 1 079 478 singleton live births was linked by Domicile Code to the New Zealand Deprivation Index, a small area index of deprivation.

RESULTS

Singleton preterm birth rates rose by 37.2% during the 20 year period, from 4.3% in 1980 to 5.9% in 1999. Rates increased by 71.9% among those living in the most affluent areas, but by only 3.5% among those living in the most deprived areas, resulting in the disappearance of a socioeconomic gradient in preterm birth that had existed during the early 1980s.

CONCLUSIONS

This study challenges traditional thinking on the associations between socioeconomic status and preterm birth. Further research is necessary if the changes that have occurred in New Zealand over the past 20 years are to be fully understood.

The epidemiology of placental infarction at term

The incidence and associations of placental infarction at term were investigated as part of a population based case-control study of small for gestational age (SGA) infants. 509 placentas from women delivering SGA infants (SGAP) and 529 placentas from women delivering infants with birthweights appropriate for gestational age (AGAP) were examined using fixed protocols for macroscopic identification and microscopic confirmation of infarction. Other information was obtained by maternal interview and from an obstetric database. Infarcts were found in 17.3 per cent of SGAP and 11.7 per cent of AGAP. This difference was in placentas with multiple infarcts not involving the placental margin and was significant in multivariate analysis (OR 1.66; 95 per cent CI 1.12,2.47). Multivariate analysis showed significant associations between the presence of any infarct and maternal hypertension in both SGAP (OR=4.00; 95 per cent CI 1.96,8.16) and AGAP (OR 2.99; 95 per cent CI 1.23,7.32); maternal smoking, associated with a lesser risk in SGAP only (OR=0.31; 95 per cent CI 0.13,0.73); maternal age at first pregnancy in a linear relationship with AGAP only (beta co-efficient 0.09, P=0.0034); and between some ethnic groups. We conclude that at least five factors have independent associations with the incidence of placental infarction and these associations differ by site and age of infarcts.