Objective To examine the association between head-to-body delivery interval (HBDI) and cord arterial pH and base excess (BE), and the risk of development of hypoxic ischaemic encephalopathy (HIE). Design Retrospective review.Setting A university hospital.Population Pregnancies complicated with shoulder dystocia during the period 1995-2009.Methods Cases were identified from a search of the hospital electronic delivery records. Cord arterial pH and BE, and the incidence of HIE and perinatal death, were retrieved from medical records and correlated with HBDI, birth weight, mode of delivery and presence of nonreassuring fetal heart rate pattern and maternal diabetes using univariate analysis, followed by multivariate analysis.Main outcome measures Any association between cord pH and HBDI.Results Of the 200 cases identified, the mean (standard deviation) HBDI was 2.5 minutes (1.5 minutes). Both HBDI and the presence of nonreassuring fetal heart rate pattern were independent factors for pH, and HBDI was the only significant factor for BE. Arterial pH dropped at a rate of 0.011 per minute [95% confidence interval (95% CI), 0.017-0.004; P = 0.002] with HBDI. The mode of delivery, birth weight and maternal diabetes did not affect blood gas levels. The respective risks of severe acidosis (pH < 7) and HIE with HBDI of <5 minutes were 0.5% and 0.5% versus 5.9% and 23.5% with HBDI ‡ 5 minutes.Conclusions Cord arterial pH drops with HBDI during shoulder dystocia, but the risk of acidosis or HIE is very low with HBDI < 5 minutes.Keywords Acidosis, base excess, head-to-body delivery interval, hypoxic ischaemic encephalopathy, shoulder dystocia, umbilical cord pH.

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Objective To evaluate the different types and sequences of manoeuvres to overcome shoulder dystocia and the rates of associated fetal injury. Design Retrospective review.Setting A university hospital.Population Pregnancies complicated with shoulder dystocia from 1995 to 2009.Methods Cases were identified from the hospital electronic delivery records.Main outcome measures The success rate between McRoberts' manoeuvre, rotational methods and posterior arm delivery, and the incidences of brachial plexus injury (BPI), clavicular fracture (CF) and humeral fracture (HF) according to the types and sequences of manoeuvres applied to overcome shoulder dystocia.Results Among 205 cases identified, McRoberts' manoeuvre was successful initially in 25% of cases, of which 7.8% suffered from BPI and 3.9% suffered from CF, but none had HF. In the failed cases, subsequent rotational methods and posterior arm delivery were similarly successful (72.0 versus 63.6%), whereas the former was associated with less BPI (4.4 versus 21.4%) and HF (1.1 versus 7.1%) despite similar risk of CF (5.6 versus 7.1%). The rotational methods were not associated with a higher fetal injury risk compared with McRoberts' manoeuvre. The remaining cases were managed by applying the third yet untried manoeuvre, and posterior arm delivery and rotational methods had similar success (77.1 versus 62.5%). The cumulative success rates after the second and the third manoeuvres were 79.0 and 94.6%, respectively.Conclusion Following the failure of McRoberts' manoeuvre, subsequent application of rotational methods and posterior arm delivery have similarly high success rates but the former may be associated with less fetal injury.

Information on the impact of maternal hepatitis B virus (HBV) infection on pregnancy outcome is conflicting. Some studies reported an association with increased infant birthweight, which could be interpreted as advantageous to pregnancy. A retrospective study was performed to compare birthweight outcome between 6261 and 55,817 singleton pregnancies in mothers screened positive and negative for hepatitis B surface antigen (HBsAg), respectively. The HBsAg positive women were younger, had higher body mass index (BMI) and incidence of overweight, but less gestational weight gain, and were associated with increased macrosomia (birthweight ≥4000 g) in mothers <35 years (odds ratio, OR, 1.28), BMI ≥25 kg/m(2) (OR 1.24), without gestational diabetes mellitus (GDM, OR 1.19), and in male infants (OR 1.18). It was also associated with increased large-for-gestational age (LGA, birthweight >90th percentile) infants in nulliparas (OR 1.13), age <35 years (OR 1.12), BMI ≥25 kg/m(2) (OR 1.19), with (OR 1.36) and without (OR 1.09) GDM, and in male infants (OR 1.13). When the effects of high BMI, advanced age, GDM, and male infants were controlled for, positive HBsAg was significantly associated with macrosomic (adjusted odds ratio, aOR, 1.15) and LGA (aOR 1.11) infants. In view of the latest findings on the association between high infant birthweight with increased risk of obesity, diabetes mellitus, and various forms of malignancies from childhood to adulthood, further studies are warranted to determine if maternal hepatitis B infection would impact adversely on the long-term health of the offspring through its effect on increasing birthweight.