1.0 Introduction
Primary postpartum haemorrhage (PPH) is one of the most common
complications of childbirth and a major cause of maternal mortality and
morbidity worldwide.(1-5) The World Health Organization (WHO) defines
primary PPH as a maternal blood loss ≥ 500 mL within the first 24 hours
of giving birth.(4, 5) Women who experience a primary PPH commonly
require greater levels of clinical intervention and care immediately
after the birth of their child and into the postpartum period.(6)
The most common cause of primary PPH is uterine atony contributing to
70-80% of all primary PPHs.(2) In high income countries such as
Australia, France, Canada, the United Kingdom (UK) and the United States
of America (USA) there has been an increased incidence of primary atonic
PPH in the last 10-20 years.(3, 6-9) However, this increase is not fully
explained with changes in known risk factors or reporting.(3)
One intervention that is anecdotally considered a potential risk factor
for primary PPH is the administration of intravenous (IV) fluids during
labour. The use of IV fluids as part of labour care is common in high
income countries such as Australia, Canada, and the USA.(10-14) It is
biologically plausible a potential relationship exists whereby larger
volumes of IV fluids could impair uterine contractility through the
development of uterine swelling (15) and/or metabolic acidosis. (16)
Additionally, dilution of clotting factors (coagulopathy)(16) or
endogenous oxytocin could be possible mechanisms. If true, these could
contribute to atonic PPH by inhibiting the myometrium from efficiently
contracting onto exposed blood vessels after placental separation and/or
preventing blood to clot effectively.
The aim of this study was to
investigate whether there is a relationship between the administration
of IV fluids during labour and primary PPH. The primary objective was to
evaluate whether the administration of high-volume IV fluids during
labour (≥ 2500 mL) increases the risk of primary PPH for women with a
term gestation, singleton pregnancy, in comparison to low-volume IV
fluids during labour (<2500 mL).