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“The suggested neonatal benefits associated with this increased placental transfusion include higher haemoglobin levels (Prendiville 1989), additional iron stores and less anaemia later in infancy (Chaparro 2006; WHO 1998b), higher red blood cell flow to vital organs, better cardiopulmonary adaptation, and increased duration of early breastfeeding (Mercer 2001; Mercer 2006). There is growing evidence that delaying cord clamping confers improved iron status in infants up to six months post birth (Chaparro 2006; Mercer 2006; van Rheenen 2004).”
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The baby/placenta has a separate blood system from the mother. The placenta does the job of the lungs by exchanging gas (oxygen and carbon dioxide) via the intervillous space between the baby’s and the mother’s blood system. Before birth, a third of the baby/placenta blood volume is in the placenta at any given time to facilitate this gas exchange.
After birth this ‘placental’ blood volume is transferred through the pulsing cord into the baby increasing the baby’s circulating blood volume. This has two major effects:
1. Provides the extra blood volume needed for the heart to direct 50% of it’s output to the lungs (8% before birth). This extra blood fills the capillaries in the lungs making them expand to provide support for the alveoli to open. It also aids lung fluid clearance from the alveoli. These changes allow the baby to breath effectively.
2. Increases the number of circulating red blood cells which carry oxygen. This increases the baby’s capacity to send oxygen around the body.
This transfer of blood volume from placenta to lungs takes place over a number of minutes following birth. Textbooks will tell you 3-7 minutes, but I have felt cords pulse for a lot longer than that. While these changes take place, oxygen continues to be provided by the placenta until the baby is ready to begin breathing.
Strange that your OB is unaware of these studies....