Hydration during labour: what are the effects of an IV drip?

Many hospitalised patients receive intravenous fluid therapy to maintain adequate hydration when fluid intake is limited. The three most common intravenous solutions for people in labour are normal saline, the Ringer's lactate and the dextrose solutions. 
 

Normal saline and Ringer's lactate are isotonic solutions, meaning they allow water to circulate freely at the cellular level without causing cells to swell or shrink. 
 

Dextrose (sugar) in water is another isotonic solution, but one that provides calories the body can use as energy. As the sugar is used up, the solution becomes hypotonic and draws water into the cells. Dextrose solutions are commonly mixed with normal saline or Ringer's lactate, as dextrose alone causes too great a drop in sodium (salt) levels in the blood of mothers and babies [1].

In a trial involving 293 women in labour, they were randomly assigned to one of three groups: oral fluids only (still water and coconut water), 

oral fluids plus intravenous Ringer's lactate at 125 ml/h, 

or oral fluids plus intravenous fluids at 250 ml/h [2]. 

But those on a drip had barely drunk any additional fluid. 

They observed: 

No difference in the duration of labour, the rate of caesarean sections, or any other complication. There were no cases of fluid overload in the lungs, also known as pulmonary oedema.

A lower risk of vomiting with a greater volume of intravenous fluids (6% vomiting in the 250 ml group, 11% in the 125 ml group, and 24% in the oral fluids group). 

In a second similar study, women either drank fluids only or were on a drip and could also drink fluids (and it was observed that they drank as much as those not on a drip) [3]. They observed that: 

The drip was associated with a reduction in the duration of labour (the first and second stages of labour were longer in those who had not received intravenous fluids)

Intravenous oxytocin increase for those not initially on a drip

No significant difference in vomiting, which is explained by the fact that they consumed the same amount of fluid.

Combining the results of these 2 studies, an average 30-minute shortening of the duration of labour for women who had been on a drip and had drunk fluids [4]. This suggests that mild dehydration could contribute to slightly longer labours. The best pregnancy food supplement during labour? Staying well hydrated. 

Studies have compared intravenous fluid infusion at 250 ml/h versus 125 ml/h on the duration of labour, caesarean sections and labour dystocia.

Fluid volume overload, also known as hypervolaemia, can occur when there is too much fluid in the blood. In cases of hypervolaemia, excess fluid can accumulate in the lungs and other tissues, and the heart has to work harder to pump the additional fluid around the body [7]. 

Effects on the newborn

The fluid overloade can cause painful swelling in the mother and excess fluid in the newborn at birth, which can lead to complications with breastfeeding when the newborn's birth weight is artificially inflated.

Risk of stopping breastfeeding

In the previous study [14], more than half (58%) of the infants in that study (whose parents intended to breastfeed) received infant formula. The reasons for this supplementation were excessive weight loss and concern about a delay in the production of mature milk.
 

Other researchers have shown that reports of excessive weight loss trigger anxiety in new mothers about their milk supply, which is then associated with the cessation of breastfeeding. They observed a more than 50% risk of stopping breastfeeding before 6 months [15]. Don't forget, mama: you don't need to look for the best post-partum food supplement to support your lactation, your body is capable of producing enough milk. 

Furthermore, the provision of infant formula in hospital independently predicts a shorter duration of exclusive breastfeeding after discharge [16].
 

In another study, Canadian researchers observed that 87% of women had started breastfeeding, but that 21% of them had stopped after one month. When asked about early weaning, breastfeeding women frequently cited sore breasts and nipples [17]. The researchers found that women who had received more intravenous fluids during labour reported greater breast tenderness after delivery and showed greater breast firmness when palpated. However, the sample size of this study was small, so the results should be interpreted with caution.

To reduce pain, a breastfeeding compress cold is very effective.

Studies show that good hydration is important during labour, particularly to help reduce its duration, and that you should drink water even if you are on a drip. So pack your water bottle, with an electrolyte solution, in your hospital bag to boost your energy levels. 

Excess fluid given by drip during labour can cause fluid overload in the mother and her newborn, resulting in weight loss at birth for the baby. 

Large volumes of intravenous fluids during labour can potentially be detrimental to breastfeeding, as this weight loss may cause anxiety for the breastfeeding mother and also lead to painful breast engorgement in the postpartum period. It is therefore important to be aware of this and not to look at birth weight as the reference, but rather the weight at 24 hours — especially if you received a drip!