Trends in place of birth for preterm infants in New South Wales, 1992-2001

The Promise of Prostaglandins: Have They Fulfilled Their Potential as Therapeutic Targets for the Delay of Preterm Birth?

OBJECTIVE

The elucidation some 30 years ago by Sir Mont Liggins that the activation of the hypothalamic-pituitary-adrenal-placental axis in fetal sheep led to elevated maternal prostaglandin (PG) concentrations and the initiation of labor provided hope that targeting PG synthesis or action would lead to effective tocolysis and lowering of the human preterm birth rate. This was the "promise of PGs."

METHODS AND RESULTS

Although early trials showed that nonsteroidal anti-inflammatory drugs (NSAIDs), which inhibit PG H synthase (PGHS), delayed preterm birth by 48 hours, other trials revealed an association between NSAIDs and adverse fetal effects, including oligohydramnios, patent ductus arteriosus, necrotizing enterocolitis, intraventricular hemorrhage, and persistent pulmonary hypertension of the newborn (PPHN). Hope was revived when studies in the mid 1990s demonstrated that much of the PGs synthesized by intrauterine tissues at preterm labor were derived from the inducible isoenzyme PGHS-2. Unfortunately, administration of specific PGHS-2 inhibitors led to the same adverse fetal effects displayed by the mixed PGHS-1 and -2 NSAIDs, causing interest in the promise of PGs to wane. This led to the development of new strategies for specific PG inhibition or antagonism. One of these is the application of a specific PGF2alpha receptor blocker, Theratechnologies (THG)113.31. THG113.31 decreases the in vitro contractile activity of mouse, sheep, and human myometrium in response to exogenous PGF2alpha, delays lipopolysaccharide (LPS)-induced preterm birth in mice, and lowers uterine electromyographic activity and delays preterm birth in sheep administered RU486. There have been no observable maternal or fetal side effects with its use.

CONCLUSION

By developing new strategies based on other therapeutic targets, the promise of PGs may once again offer hope for delaying preterm birth.

Trends in planned early birth: a population-based study

OBJECTIVE

The purpose of this study was to describe trends and outcomes of planned births.

STUDY DESIGN

Data from linked birth and hospital records for 779,521 singleton births at ≥33 weeks' gestation from 2001-2009 were used to determine trends in planned births (prelabor cesarean section and labor inductions). Adverse outcomes were composite indicators of maternal and neonatal morbidity/death.

RESULTS

From 2001-2009, there were increases in labor inductions and prelabor cesarean deliveries at <40 weeks' gestation, but no decrease in the stillbirth rate (trend P = .34). By 2009, 14.9% of live births at ≥33 weeks' gestation were prelabor cesarean deliveries before the due date; 11.4% were inductions. As planned births increased, maternal risks shifted, which included a decline in inductions with maternal hypertension from 31.9-23.9%. Earlier birth was contemporaneous with increases (trend P < .001) in neonatal and maternal morbidity rates from 3.0-3.2% and 1.1-1.5%, respectively.

CONCLUSION

Planned birth before the due date is increasing without a contemporaneous reduction of stillbirths.

The long-term effects of prematurity and intrauterine growth restriction on cardiovascular, renal, and metabolic function

Objective. To determine relative influences of intrauterine growth restriction (IUGR) and preterm birth on risks of cardiovascular, renal, or metabolic dysfunction in adolescent children. Study Design. Retrospective cohort study. 71 periadolescent children were classified into four groups: premature small for gestational age (SGA), premature appropriate for gestational age (AGA), term SGA, and term AGA. Outcome Measures. Systolic blood pressure (SBP), augmentation index (Al), glomerular filtration rate (GFR) following protein load; plasma glucose and serum insulin levels. Results. SGA had higher SBP (average 4.6 mmHg) and lower GFR following protein load (average 28.5 mL/min/1.73 m²) than AGA. There was no effect of prematurity on SBP (P = .4) or GFR (P = .9). Both prematurity and SGA were associated with higher AI (average 9.7%) and higher serum insulin levels 2 hr after glucose load (average 15.5 mIU/L) than all other groups. Conclusion. IUGR is a more significant risk factor than preterm birth for later systolic hypertension and renal dysfunction. Among children born preterm, those who are also SGA are at increased risk of arterial stiffness and metabolic dysfunction.

Twin deliveries and place of birth in NSW 2001-2005

BACKGROUND

Twin pregnancies have an elevated risk of adverse outcomes, particularly preterm twins.

AIMS

Describe the distribution of twin deliveries by hospital level, the associated perinatal and maternal morbidity, and determine predictors of perinatal morbidity and urgent transfer to a neonatal intensive care unit.

METHODS

Longitudinally linked New South Wales delivery and hospital records for the years 2001-2005 were used to identify perinatal and maternal morbidity/mortality in twin pregnancies. Regression analysis was used to examine predictive factors, including birth hospital volume.

RESULTS

At < or = 32 weeks, 88.1% of twins were delivered in tertiary referral hospitals. By 34-35 weeks, only 39.7% of twins were delivered in tertiary units. Gestational age was the primary predictor of perinatal morbidity/mortality. Perinatal morbidity/mortality and maternal morbidity were lowest for deliveries at 38 weeks. There was no evidence that planned caesarean section at < or = 38 weeks was protective against perinatal morbidity/mortality. There was an increased risk of perinatal morbidity/mortality (odds ratio (OR) = 2.22) for twins delivered at 33-35 weeks gestation at hospitals with < 500 deliveries per annum, and an increased risk of urgent neonatal transfer (OR = 2.06). Twin pairs for whom there was a > or = 20% discordance in birthweight had an increased risk of morbidity/mortality at 36-38 weeks (OR = 1.79).

CONCLUSIONS

Both infant and maternal morbidity increase from 39 weeks gestation. Delivery of twins before 36 weeks at smaller hospitals (< 500 deliveries per annum) should be avoided. A twin pregnancy where there is a > or = 20% difference in estimated fetal weights should be considered for referral to a tertiary obstetric unit.

Perinatal care at the borderlines of viability: a consensus statement based on a NSW and ACT consensus workshop

Perinatal care at the borderlines of viability demands a delicate balance between parents' wishes and autonomy, biological feasibility, clinicians' responsibilities and expectations, and the prospects of an acceptable long-term outcome - coupled with a tolerable margin of uncertainty. A multi-professional workshop with consumer involvement was held in February 2005 to agree on management of this issue in New South Wales and the Australian Capital Territory. Participants discussed and formulated consensus statements after an extensive consultation process. Consensus was reached that the "grey zone" is between 23 weeks' and 25 weeks and 6 days' gestation. While there is an increasing obligation to treat with increasing length of gestation, it is acceptable medical practice not to initiate intensive care during this period if parents so wish, after appropriate counselling. Poor condition at birth and the presence of serious congenital anomalies have an important influence on any decision not to initiate intensive care within the grey zone. Women at high risk of imminent delivery within the grey zone should receive appropriate and skilled counselling with the most relevant up-to-date outcome information. Management plans can thus be made before birth. Information should be simple, factual and consistent. The consensus statements developed will provide a framework to assist parents and clinicians in communication, decision making and managing these challenging situations.

Improved outcomes of extremely premature outborn infants: effects of strategic changes in perinatal and retrieval services

OBJECTIVE

The goal was to evaluate the impact of statewide coordinated changes in perinatal support and retrieval services on the outcomes of extremely premature births occurring outside perinatal centers in the state of New South Wales, Australia.

METHODS

The intervention included additional, network-coordinated, perinatal telephone advice to optimize in utero transfers and centralization of the neonatal retrieval system, with preferential admission of retrieved infants (outborn infants) to perinatal centers instead of freestanding pediatric hospitals, from the middle of 1995. Population birth and NICU admission cohorts of infants of 23 to 28 weeks of gestation were studied. Outcomes of epoch 1 (1992 to the middle of 1995; 1778 births and 1100 NICU admissions) were compared with those of epoch 2 (1997-2002; 3099 births and 2100 NICU admissions), after an 18-month washout period.

RESULTS

There were 25% fewer nontertiary hospital live births (19.7% vs 14.9%) and more prenatal steroid use. Despite an 11.4% average annual increase in NICU admissions between the 2 epochs, fewer infants were outborn (12.0% vs 9.3%) and outborn mortality rates decreased significantly (39.4% vs 25.1%), particularly for those between 27 and 28 weeks of gestation. The overall improvement was equivalent to 1 extra survivor per 16 New South Wales births. There were also significantly fewer serious outcome morbidities in outborn infants during epoch 2, over the improvements in inborn infants.

CONCLUSIONS

Statewide coordinated strategies in reducing nontertiary hospital births and optimizing transport of outborn infants to perinatal centers have improved considerably the outcomes of extremely premature infants. These findings have vital implications for health outcomes and resource planning.

Does size matter? A population-based study of birth in lower volume maternity hospitals for low risk women

OBJECTIVE

To study the association between volume of hospital births per annum and birth outcome for low risk women.

DESIGN

Population-based study using the National Perinatal Data Collection (NPDC).

SETTING

Australia.

PARTICIPANTS

Of 750,491 women who gave birth during 1999-2001, there were 331,147 (47.14%) medically 'low risk' including 132,696 (40.07%) primiparae and 198,451 (59.93%) multiparae.

METHODS

The frequency of each birth and infant outcome was described according to the size of the hospital where birth took place. We investigated whether unit size (defined by volume) was an independent risk factor for each outcome factor using public hospitals with greater than 2000 births per annum as a reference point.

MAIN OUTCOME MEASURES

Rates of intervention at birth and neonatal mortality for low risk women in relation to hospitals with <100, 100-500, 501-1000, 1001-2000 and >2001 births per annum.

RESULTS

Neonatal death was less likely in hospitals with less than 2000 births per annum regardless of parity. For multiparous low risk women in hospitals of 100 and 500 births per annum compared with hospitals of >2000 births per annum the adjusted odds of neonatal mortality [adjusted odds ratio (AOR) 0.36; 99% confidence interval (CI) 0.14-0.93]. For low risk primiparous women in hospitals with less than 100 births per annum, there were lower rates of induction of labour (AOR 0.62; 99% CI 0.54-0.73); intrathecal analgesia/anaesthesia (AOR 0.34; 99% CI 0.28-0.42); instrumental birth (AOR 0.80; 99% CI 0.69-0.93); caesarean section after labour (AOR 0.59; 99% CI 0.49-0.72) and admission to a neonatal unit (AOR 0.15; 99% CI 0.10-0.22) and for low risk multiparous women in hospitals with less than 100 births per annum: induction (AOR 0.69; 99% CI 0.62-0.76); intrathecal analgesia/anaesthesia (AOR 0.32; 99% CI 0.29-0.36); instrumental birth (AOR 0.52; 99% CI 0.41-0.67); caesarean section after labour (AOR 0.41; 99% CI 0.33-0.52); and admission to a neonatal unit (AOR 0.09; 99% CI 0.07-0.12).

CONCLUSIONS

In Australia, lower hospital volume is not associated with adverse outcomes for low risk women.