SUMMARY1. Foetal breathing movements, electrocortical activity, arterial pressure and heart rate were recorded continuously in chronically catheterized sheep, 97-145 days pregnant.2. With increasing gestational age there was a fall in heart rate of 0*67 beats/day and a rise in arterial pressure of 0-46 mmHg/day.3. Hypoxaemia in the foetus was induced by allowing the ewe to breathe low oxygen mixtures, 9 % 02 with 3 % CO2 in N2. In the younger foetuses there was an initial rise in heart rate whereas in the older foetuses there was a fall. After the end of hypoxia there was a persistent tachycardia in both groups. In the older foetuses there was a rise of arterial pressure. 4. Two vagotomized older foetuses showed cardiovascular responses similar to those of the younger foetuses.5. Foetal breathing movements were abolished by hypoxaemia in twenty-two of twenty-five experiments. In the three exceptional experiments there was a small rise in Pa co2 6. The proportion of time occupied by low voltage electrocortical activity in the foetus was reduced by hypoxaemia.7. Hypercapnia was induced by giving the ewe 4-6 % CO2 with 18 % 02 in N2 to breathe. After an initial slight fall the foetal heart rate increased and there was a small rise in foetal arterial pressure.8. The proportion of time occupied by low voltage electrocortical activity and breathing movements was increased by hypercapnia.9. Maternal hyperoxia, induced by giving 50 % 02 in N2, did not significantly increase foetal breathing movements unless the ewe was in labour. In labour the foetuses had lower Pa 02 values initially and a reduced incidence of foetal breathing, both of which were increased by maternal hyperoxia.

Background Overweight and obesity during pregnancy is an increasing health problem.Objective A systematic review to assess the benefits and harms of antenatal dietary or lifestyle interventions for pregnant women who are overweight or obese.Search strategy The Cochrane Controlled Trials Register (CENTRAL) was searched (last search January 2010). Reference lists of retrieved studies were searched by hand. No date or language restrictions were used.Selection criteria Randomised controlled trials comparing antenatal dietary and/or lifestyle or other interventions with no treatment for overweight or obese women were considered. Studies were evaluated independently for appropriateness for inclusion and methodological quality. The primary outcome was large-for-gestational-age infants.Data collection and analysis Nine randomised controlled trials were included involving 743 women who were overweight or obese during pregnancy. Seven trials compared a dietary intervention with standard antenatal care.Main results There were no statistically significant differences identified between women who received an antenatal intervention and those who did not for the large-for-gestational-age infant outcome (three studies; 366 women; risk ratio 2.02; 95% CI 0.84, 4.86) or mean gestational weight gain [four studies; 416 women; weighted mean difference )3.10 kg; 95% CI )8.32, 2.13 (randomeffects model)]. There were no statistically significant differences identified for other reported outcomes.Author's conclusions The effect of providing an antenatal dietary intervention for overweight or obese pregnant women on maternal and infant health outcomes remains unclear.

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