Vaginal birth versus elective caesarean section: effects on gastric function in the neonate

Area of Science:

• Endocrinology
• Neonatal Physiology
• Gastroenterology

Background:

• Plasma gastrin concentrations increase in late gestation, peaking around birth (neonatal hypergastrinaemia).
• The role of cortisol in mediating these changes, particularly in relation to birth mode, is not fully understood.

Purpose of the Study:

• To investigate the hypothesis that the final rise in plasma cortisol during spontaneous vaginal birth influences neonatal gastrin and gastric acid secretion.
• To examine the effects of cortisol manipulation in the immediate postnatal period on gastrin and related parameters in piglets.

Main Methods:

• Comparison of vaginally delivered (VD) and caesarean-delivered (CD) piglets immediately after birth.
• Measurement of plasma cortisol, plasma gastrin, gastric fluid pH, and antral gastrin concentrations.
• Postnatal administration of saline, metyrapone (cortisol synthesis inhibitor), or ACTH to CD piglets.

Main Results:

• Newborn VD pigs exhibited significantly higher plasma cortisol and gastrin, and lower gastric fluid pH compared to CD pigs.
• Plasma cortisol levels correlated significantly with plasma gastrin and gastric fluid pH in newborn pigs.
• Postnatal ACTH treatment (elevated cortisol) led to lower plasma gastrin, while metyrapone (low cortisol) did not significantly differ from controls.

Conclusions:

• High circulating cortisol levels during the intrapartum period stimulate the normal rise in gastrin and acid secretion associated with spontaneous vaginal delivery in piglets.
• Cortisol is unlikely to play a significant role in the postnatal development of gastrin and acid secretion in the immediate post-birth period.