A Low Blood Pressure Reading That May Be Best Left Alone

Understanding a 2025 review that asked whether premature babies with only a low blood pressure number need treatment

When a premature baby in intensive care shows a low blood pressure but is otherwise pink, warm, and doing well, doctors have long debated whether to treat that number at all. A 2025 international review pulled together 44 studies to answer the question and reached a careful, reassuring conclusion: in the first day of life, a low blood pressure on its own — with no other sign that the baby's organs are short of blood flow — may be safer left untreated than pushed back up with medication.

Why This Question Matters

Blood pressure in a tiny premature baby is one of the most closely watched numbers on the monitor, and for good reason: blood pressure helps push blood, and therefore oxygen, to the brain and other organs. For decades, neonatal teams used a simple rule of thumb — the blood pressure number should be at least as high as the baby's gestational age in weeks. If a baby born at 25 weeks had a reading below 25, that counted as "low," and the reflex was often to treat it with extra fluid or a medicine such as dopamine that raises blood pressure [1].

The trouble is that this rule was never really tested against what happens to babies afterward. More than fifteen years ago, a careful review of the evidence found surprisingly little proof that raising a low blood pressure actually helped babies do better [2]. Even so, treatment habits varied enormously: studies showed that whether a baby received blood-pressure medicine depended more on which hospital cared for them than on anything measurable about the baby [3]. Two babies with identical readings might be treated very differently a few miles apart.

Part of the difficulty is that the blood pressure number is only an indirect clue to what doctors really care about: whether blood is reaching the organs. A baby can have a low reading while their circulation is perfectly adequate — good colour, warm skin, a normal heart rate, and steady urine output. Doctors came to call this situation isolated hypotension: a low blood pressure with no other warning signs. It is different from a low blood pressure that comes alongside real signs of trouble, such as a racing heart, sluggish circulation in the hands and feet, or rising acid levels in the blood. That second situation is genuine and needs prompt attention. The unsettled question was what to do about the first one — the low number by itself [4].

What the Researchers Did

A group of neonatal specialists brought together by the National Neonatal Forum in India carried out what is known as a systematic review: a structured search for every relevant study, followed by a careful pooling of their results. They compared two approaches in premature babies (born before 37 weeks) during their first week of life. One approach was "active" — giving medication to raise an isolated low blood pressure. The other was "restrictive" — holding off unless the baby also showed signs of poor blood flow [4].

After screening more than 2,000 studies, they included 44. Only two were randomised controlled trials, the gold standard in which babies are assigned by chance to one approach or the other. One was the HIP trial, which compared dopamine against a dummy (placebo) infusion but had to stop early because too few families could be enrolled [5]. The other was a small pilot trial testing different blood-pressure treatment thresholds [6]. Because these trials were small, most of the useful information came from the larger observational studies, which followed babies who had been treated or not treated in ordinary care. The team then graded how trustworthy the combined evidence was — and, importantly, they were honest that it was weak.

What They Found

The randomised trials, taken together, could not show that treating an isolated low blood pressure made any clear difference — not to survival, not to bleeding in the brain, not to a serious bowel illness called necrotising enterocolitis [4][,5][,6]. The numbers were too small to be sure either way.

The most striking pattern came from the larger real-world studies, and it turned on timing. When doctors treated an isolated low blood pressure during the very first 24 hours of life, babies were roughly twice as likely to have serious bleeding or injury in the brain. But when treatment happened a little later — between one and three days of age — the pattern reversed, and treated babies actually appeared to have fewer brain injuries and less bowel disease [7]. Looking further ahead, treating in that first day was also linked to a higher chance of developmental difficulties by around two years of age [8] and to a greater risk of hearing loss [9]. The researchers were careful to stress that all of these findings are uncertain — they are meaningful warning signs rather than firm proof.

There is a sensible biological explanation for why early treatment might backfire. In the first day after birth, a premature baby's blood pressure naturally tends to rise on its own as the body adjusts to life outside the womb. Forcing it up with medication can make the pressure swing up and down, and those swings — rather than a steadily low number — seem to be what the fragile blood vessels in a premature brain tolerate least well. Studies have long shown that the usual blood-pressure cut-offs are poor predictors of which babies actually develop brain injury [10].

What This Means for Families and Their Baby's Care

The review led to two gentle, carefully worded suggestions. In the first 24 hours of life, if a premature baby has only a low blood pressure and no other sign of poor circulation, the team may reasonably choose to watch closely rather than treat. There is an important safety net: if the pressure drops very low — well below what is expected for the baby's gestational age — treatment is still appropriate even in that first day. Between one and three days of age, treating an isolated low blood pressure becomes more reasonable [4].

For parents, the key thing to understand is that "watching and waiting" is not the same as "doing nothing." Before deciding to hold off, the team actively checks that the baby's circulation really is healthy — heart rate, skin colour and warmth, capillary refill, urine output, and blood tests. If any of those point to genuine trouble, the baby is treated. So a decision not to give blood-pressure medicine is itself the result of a careful assessment showing the baby is doing well. If you are ever unsure why a low number on the monitor is not being treated, it is entirely reasonable to ask your baby's nurse or doctor to walk you through what they are seeing.

It also helps to understand why the age of the baby matters so much. In the first hours after birth, a premature baby's body is going through an enormous transition — the circulation that ran through the placenta is switching over to breathing and pumping blood on its own. During this settling-in period, blood pressure naturally drifts and then tends to climb, and the baby's brain has some built-in ability to keep its own blood flow steady even when the pressure on the monitor looks low. Adding a medicine that pushes the pressure up can overshoot and create swings, and the delicate blood vessels in a very premature brain seem to cope worst with swings. After the first day, once the baby has stabilised, that calculation shifts, which is why the same low reading may be treated differently depending on whether the baby is a few hours or a few days old [4][,7].

None of this means a low blood pressure is ignored. A low number is always a prompt for the team to look harder at the baby — and if genuine signs of poor circulation appear, treatment follows promptly. What the review argues against is treating the number reflexively, before checking whether the baby actually needs it. This distinction matters because, for decades, so much depended simply on local habit that two similar babies could be managed very differently [3], and because the usual blood-pressure cut-offs turned out to be poor at predicting which babies would actually be harmed [10]. A more thoughtful, baby-centred approach aims to spare infants medicines they do not need while never withholding care from one who does.

What Researchers Are Working On Next

The honest bottom line from this review is that the evidence is thin, and the authors call clearly for larger, better trials that separate babies by both how premature they are and how old they are in days [4]. Such trials are genuinely hard to run — families are understandably reluctant to enrol a fragile newborn, and doctors themselves often disagree about the right thing to do, which are exactly the barriers an earlier feasibility study identified [11]. A recent follow-up of the HIP trial babies at two years of age hinted that those who received dopamine may have done slightly better, though the difference was not large enough to be certain [12]. Until stronger answers arrive, the guiding principle is a humane and practical one: care for the baby in front of you, not just the number on the screen.

References

  1. Dempsey EM, Barrington KJ, Marlow N, O'Donnell CPF, Miletin J, Naulaers G, et al. Hypotension in Preterm Infants (HIP) randomised trial. Arch Dis Child Fetal Neonatal Ed. 2021;106(4):398–403. doi:10.1136/archdischild-2020-320241 ↩
  2. Dempsey EM, Barrington KJ. Treating hypotension in the preterm infant: when and with what: a critical and systematic review. J Perinatol. 2007;27(8):469–78. doi:10.1038/sj.jp.7211774 ↩
  3. Batton B, Li L, Newman NS, Das A, Watterberg KL, Yoder BA, et al. Use of antihypotensive therapies in extremely preterm infants. Pediatrics. 2013;131(6):e1865–73. doi:10.1542/peds.2012-2779 ↩
  4. Ramaswamy VV, Kumar G, Pullattayil S AK, Aradhya AS, Suryawanshi P, Sahni M, et al. Active versus restrictive approach to isolated hypotension in preterm neonates: A Systematic Review, Meta-analysis and GRADE based Clinical Practice Guideline. PLoS One. 2025;20(3):e0309520. doi:10.1371/journal.pone.0309520 ↩
  5. Dempsey EM, Barrington KJ, Marlow N, O'Donnell CPF, Miletin J, Naulaers G, et al. Hypotension in Preterm Infants (HIP) randomised trial — dopamine versus placebo. Arch Dis Child Fetal Neonatal Ed. 2021;106(4):398–403. doi:10.1136/archdischild-2020-320241 ↩
  6. Pereira SS, Sinha AK, Morris JK, Wertheim DF, Shah DK, Kempley ST. Blood pressure intervention levels in preterm infants: pilot randomised trial. Arch Dis Child Fetal Neonatal Ed. 2019;104(3):F298–305. doi:10.1136/archdischild-2017-314159 ↩
  7. Durrmeyer X, Marchand-Martin L, Porcher R, Gascoin G, Roze J-C, Storme L, et al. Abstention or intervention for isolated hypotension in the first 3 days of life in extremely preterm infants: association with short-term outcomes in the EPIPAGE 2 cohort study. Arch Dis Child Fetal Neonatal Ed. 2017;102(6):F490–6. doi:10.1136/archdischild-2016-312104 ↩
  8. Batton B, Li L, Newman NS, Das A, Watterberg KL, Yoder BA, et al. Early blood pressure, antihypotensive therapy and outcomes at 18–22 months' corrected age in extremely preterm infants. Arch Dis Child Fetal Neonatal Ed. 2016;101(3):F201–6. doi:10.1136/archdischild-2015-308899 ↩
  9. Kuint J, Barak M, Morag I, Maayan-Metzger A. Early treated hypotension and outcome in very low birth weight infants. Neonatology. 2009;95(4):311–6. doi:10.1159/000180113 ↩
  10. Limperopoulos C, Bassan H, Kalish LA, Ringer SA, Eichenwald EC, Walter G, et al. Current definitions of hypotension do not predict abnormal cranial ultrasound findings in preterm infants. Pediatrics. 2007;120(5):966–77. doi:10.1542/peds.2007-0075 ↩
  11. Batton BJ, Li L, Newman NS, Das A, Watterberg KL, Yoder BA, et al. Feasibility study of early blood pressure management in extremely preterm infants. J Pediatr. 2012;161(1):65–9.e1. doi:10.1016/j.jpeds.2012.01.014 ↩
  12. Miletin J, Semberova J, Martin J, Janota J, O'Donnell CPF, Dempsey EM, et al. Outcomes of extremely preterm infants who participated in a randomised trial of dopamine for treatment of hypotension (the HIP trial) at 2 years corrected age. Arch Dis Child Fetal Neonatal Ed. 2025. doi:10.1136/archdischild-2024-327894 ↩