Objective To estimate the changes in risk of intrapartum caesarean delivery and perinatal distress that may be introduced through increased birth size, resulting from interventions such as improving nutrition of the mother; and to characterise delivery risk relative to maternal stature by birth size. Design Model these risks using data from the Guatemalan Perinatal Study. Setting The antenatal clinic of the Gynaecology and Obstetrics Hospital of the Guatemalan Social Security Institute in Guatemala City serving predominantly working class women. Population Women who had their first prenatal visit between April 1984 and January 1986. Methods Multivariate logistic regression models were developed to estimate incidence of intrapartum caesarean delivery and perinatal distress and used to calculate changes in risk associated with changes in size. Main outcome measures Incidences of intrapartum caesarean delivery and perinatal distress. Results A woman of 146cm height (‐1 SD) relative to another of 160cm (+1 SD) has a 2.5 times higher risk of intrapartum caesarean delivery. An increase in newborn head circumference and weight (from ‐1 SD to +1 SD) are each independently associated with an increase in risk of intrapartum caesarean delivery (2.0 times and 1.5 times, respectively). An increase in birthweight from 2,450 g to 2,550 g is associated with a decrease in risk of perinatal distress of 34/1000 cases and an increase in risk of intrapartum caesarean delivery of 8/1000 cases. Conclusions Increases in fetal growth comparable to those attributable to improved nutrition during pregnancy are associated with a larger decrease in risk of perinatal distress relative to the increase in risk of intrapartum caesarean delivery for the mother. Greater maternal stature is associated with lower risk of intrapartum caesarean delivery.

In many regions of the world, women breastfeed one child while pregnant with the next. Among rural Guatemalan women participating in a nutrition-supplementation trial, lactation overlapped with pregnancy in 253 of 504 (50.2%) of the pregnancies. For cases where overlap occurred, 41.4% continued to breast-feed into the second trimester and 3.2%, in the third trimester. The maternal and fetal responses to the energetic stresses of overlap and of the duration of the recuperative (nonpregnant, nonlactating) interval were assessed. Overlap resulted in increased supplement intake. Short recuperative periods (less than 6 mo) resulted in increased supplement intake and reduced maternal fat stores. The energetic stresses of overlap and short recuperative periods did not significantly affect fetal growth. The mother appears to buffer the energetic stress, protecting fetal growth. This research demonstrates that evidence of depletion of maternal nutrient stores caused by a demanding reproductive history is found when reproductive stress is characterized adequately.

Frequent cycles of reproduction increase the risk that lactation will overlap with pregnancy and shorten the duration of the recuperative interval (nonpregnant and nonlactating portion) within the reproductive cycle, thereby increasing the risk of maternal nutritional depletion. Nutritional responses to these stresses have been demonstrated by contrasting groups of women with different experiences; however, these relationships may be spurious and the result of third factors. In this study, responses to changing stress over consecutive pregnancies were studied and contrasted within individual Guatemalan women; biases caused by factors constant to women were eliminated. Stress was assessed by examining responses in maternal supplement intake, maternal fat stores, and birth weight. Overlap and short recuperative intervals were found to be stressful (in that order) for mothers as shown by increased supplement intake and reduced fat stores. Birth weight in term gestations was not affected, indicating that fetal growth is being protected at the cost of maternal nutritional status.

Objective To estimate the changes in risk of intrapartum caesarean delivery and perinatal distress that may be introduced through increased birth size, resulting from interventions such as improving nutrition of the mother; and to characterise delivery risk relative to maternal stature by birth size.Design Model these risks using data from the Guatemalan Perinatal Study.Setting The antenatal clinic of the Gynaecology and Obstetrics Hospital of the Guatemalan Social Security Institute in Guatemala City serving predominantly working class women. Population Women who had their ®rst prenatal visit between April 1984 and January 1986.Methods Multivariate logistic regression models were developed to estimate incidence of intrapartum caesarean delivery and perinatal distress and used to calculate changes in risk associated with changes in size. Main outcome measures Incidences of intrapartum caesarean delivery and perinatal distress.Results A woman of 146cm height (-1 SD) relative to another of 160cm (11 SD) has a 2.5 times higher risk of intrapartum caesarean delivery. An increase in newborn head circumference and weight (from -1 SD to 11 SD) are each independently associated with an increase in risk of intrapartum caesarean delivery (2.0 times and 1.5 times, respectively). An increase in birthweight from 2,450 g to 2,550 g is associated with a decrease in risk of perinatal distress of 34/1000 cases and an increase in risk of intrapartum caesarean delivery of 8/1000 cases. Conclusions Increases in fetal growth comparable to those attributable to improved nutrition during pregnancy are associated with a larger decrease in risk of perinatal distress relative to the increase in risk of intrapartum caesarean delivery for the mother. Greater maternal stature is associated with lower risk of intrapartum caesarean delivery.

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