What does it mean when there is meconium in the waters? Is your baby at risk? Should you transfer to hospital?
One common reason for transferring to hospital from a homebirth is that meconium is found in the waters. This means that the baby has had a bowel movement before or during labour, and it is a sign that the baby possibly is, or has been, in distress, OR that the baby's gut is mature. Unfortunately it can be hard to tell which reason applies, which is why standard practice is to be cautious if meconium is present.
Amniotic fluid is normally clear, often with flecks of white vernix - if it is coloured then usually meconium has been passed. The midwife can tell from the colour of the waters whether the meconium is fresh or old. If the waters are greenish, the meconium was passed recently. If the waters are brownish or golden, this suggests the meconium is old, ie was passed some time ago.
In many areas there is a blanket recommendation that the mother should always transfer to hospital if meconium has been passed. In other cases, mothers and midwives may be happy for the labour to continue at home if the baby appears to be coping well with the labour. For example, if the meconium is clearly old, all this tells us is that the baby might have been in distress at some point in the past, or that its gut is mature, and if there are no signs of current problems then the mother and midwife may be happy to continue with a home birth.
Here is a brief summary of the issues - more details and references below.
Although you will normally be advised to transfer to hospital if meconium is found in the waters at a planned homebirth, as always, the decision belongs to you alone. Your midwife may be required by her employer's policies to recommend that you transfer, regardless of what her clinical opinion of the situation is. It is certainly worth taking time to discuss with your midwife what her own view of the situation is, and whether she believes that your baby is in good shape or not. Below I have outlined questions I would ask if this situation occurred - your own priorities may, of course, be different.
If I were at home and the baby's heart rate was showing signs of distress, which was not relieved by simple measures like trying new positions, then I'd wonder why. I personally would transfer to hospital regardless of whether there was meconium or not in this situation, because a healthy baby should be able to cope with a normal labour, and if my baby wasn't coping, I wouldn't want to stick around at home to find out why.
But IF there was meconium and the baby's heart rate was fine... if it was thin, well-diluted, I wouldn't worry too much. If it was thick - but the heart rate was still fine - ... I'd probably lean heavily on the clinical judgement of the midwife, and consider how far advanced my labour was. Is there time to transfer to hospital, or is it better to push the baby out quickly at home?
If my baby was postdates and my waters had gone then I might think the thick meconium just hadn't had time to get diluted by amniotic fluid, and was due to gut maturity. But if the baby was early... again, I'd be wondering why baby had passed meconium. Why wasn't there enough fluid to dilute it? Low fluid levels mean it's easier for the cord to get compressed in labour, for instance. What did my midwife think, based on her experience?
Here are some extracts from Lesley Page's book: 'The New Midwifery' ed. Lesley Ann Page, pub Churchill Livingstone, 2000. Lesley Page is a Professor of Midwifery and well-known as an author and expert witness.
EXTRACTS from Ch 1 - Putting Science and Sensitivity into practice.
======= END OF QUOTES FROM "THE NEW MIDWIFERY".====
Despite evidence to the contrary.. the presence of any meconium at all in the amniotic fluid is still, in many healthy services, treated as if it were an independent marker of fetal distress and as if it led directly to meconium aspiration syndrome. In a comprehensive review of the subject, Katz & Bowes (1992) questioned three fundamental assumptions about meconium:
- that the presence of meconium ... is an independent marker of fetal distress;
- that mec. aspiration primarily occurs when the fetus gasps at birth or in uters, in response to severe asphyxia;
- that meconium aspiration syndrome (MAS) is the result of the deleterious effect of the inhaled meconium on the neonatal lungs.
The fetus is more likely to pass meconium into the amniotic fluid as it matures. The passage may be physiological or may be caused by a transient episode such as a cord or head compression causing a vagal response. Some fetuses with meconium-stained amniotic fluid will be compromised; many will not.
MECONIUM AND FETAL DISTRESS
The passage of meconium is common at term and frequent in the post-dated pregnancy. It is estimated as occurring in between 12% (Katz & Bowes 1992) and 13% of all live births, incraseing to 30% at 40 weeks and 50% at 42 weeks... the identification of fetal distress when there is mec-stained amniotic fluid depends on careful fetal heart monitoring (K&B, Danelian)
DO THIN AND THICK MEC DIFFER IN SIGNIFICANCE AND WHY?
Thick mec is thick because it is not diluted with amniotic fluid, either because of oligohydramnios or because the membranes have ruptured. Reduced amniotic fluid both reflects reduced uterine placental sufficiency and predisposes to fetal compromise because of the likelihood of cord compression. Thick mec is more likely to be aspirated. 95% of cases of MAS develops in the presence of thick mec (K&B 1992). Thick mec is therefore more likely to be associated with fetal distress.
WHAT IS THE CAUSE OF MECONIUM ASPIRATION SYNDROME (MAS)?
Meconium aspiration is an antepartum intrauterine event, which occurs either with gasping or with deep breathing. Mec aspiration is defined as the presence of mec below the vocal cords. It is estimated to occur in 11-58% (mean 35%) of live births with mec -stained liquor, approx. 4% of all live births. Whereas it was once believed that MAS, a potentially serious condition with an associated mortality of up to 40%, was caused by mec aspiration, there is now evidence to the contrary. MAS occurs in only 5-10% of infants with mec below the vocal cords. MAS is initiated by pulmonary vascular disease that is caused by fetal hypoxia and asphyxia. Although the primary cause of the condition or hypoxia or asphyxia, the presence of mec in the lungs compounds it. MAS is a thus multifaceted condition. Although 5% of cases develop in the presence of thin meconium, the associated respiratory disease is mild.
HOW SHOULD LABOUR AND BIRTH BE MANAGED?
The first concern is whether fetus is at higher risk of distress. K&B recommend that identification of high risk should be by clinical observation and selective antepartum testing for reduced amniotic fluid if the fetus is post-term.
Second is the issue of identifying fetal distress.. K&B advise careful fetal heart rate monitoring when there is mec-stained amniotic fluid. If mec is thick, electronic fetal monitoring is advised..
Third, is suctioning the nasopharynx and trachea justified? given that aspiration is intrauterine and does not occur during birth, suctioning ... to prevent MAS is not logical. A number of studies have brought into question the efficacy of suctioning these areas. ... Suctioning, particularly intubation and tracheal suctioning, is likely to be traumatic and to induce brady cardia because of vagal response. The airway may need to be cleared if mec is obstructing ventilation. Otherwise, suctioning is only recommended if there have been signs of fetal distress.... If there have been signs of .. distress, a paediatrician should be present for the birth in case resus is required.
Martine's first baby was postdates. When her waters broke, meconium was present but labour was progressing so quickly, and the baby's heartbeat was so good, that the midwife supported her at home. Baby born in excellent condition.
Sarah B: There was both old and new meconium in the waters, but the baby's heart rate was reassuring and labour progressing quickly, so the midwife advised expectant management at home, and baby Iris was born in great condition.
Cassandra's waters broke in late labour and it was clear the baby had passed meconium. Her midwives were watchful, but did not advise transfer.
Amanda B entered the second stage of labour just as meconium was found in her waters. The midwife asked her to push hard to deliver the baby quickly, with an ambulance on its way. He was fine.
Nicola H transferred to hospital and had an emergency caesarean when baby Isabelle passed meconium and showed other signs of distress. It's clear that, although this is not the birth Nicola had hoped for, it is the one she needed.
Helen M's baby passed meconium as he was born - his heart rate had dipped just before and Helen pushed him out quickly.
Rachel Stacey planned a home waterbirth, but when her waters broke before labour started, there was meconium. She went to hospital for monitoring, and when this suggested that her baby was perfectly happy, she made the controversial choice to return home and continue with her plans.
Rachael Keith had already transferred to hospital when meconium was found in the waters, and her baby's heart rate was showing signs of distress. Baby Matilda was a brow presentation, and was born by emergency c-section.
Rebecca writes: "She was quiet and a bit blue and seemed slow to get going... they picked her up and stood by the window with her to assess her colour properly. It turned out she'd pooped a little before birth and had swallowed some of the meconium and had a lot of slime in her passages. They suctioned out her nose and throat and gave her some oxygen. As she started to pink up they put her on my chest again and she really got going then. "
Rachel White planned a homebirth after two caesareans. Her baby was occiput posterior and presenting brow-first, making labour tough and painful, and baby Jaya passed meconium before birth. Supported wonderfully by her doula, partner and NHS midwives, Rachel still managed to deliver her baby at home.
Helen O'Donnell's baby had meconium in her waters when she was born - her waters didn't break beforehand. Helen says Daisy was absolutely fine, apart from throwing up meconium a few times during the night.
Lorna found meconium when her waters went at 5-6cm dilation. Her midwife advised transfer but Lorna asked her to monitor the baby's heart, and when that was fine, decided to stay at home.
Aida's sixth baby was born at home; thick meconium was visible just minutes before the birth, and baby Maia needed resuscitation, but this was handled safely at home.
Becky transferred to hospital for the birth of her first baby when meconium was present in the waters. She came under some pressure to accept various interventions in, and limitations on, her labour because of this, but she still managed to have a positive and natural birth.
Catriona's fourth baby had meconium in his waters, but as the bag of waters only broke at the end of labour, it was too late for this to be an issue. He was born at home, safe and well, four minutes later.
Gillian's first baby, born in hospital, and her second, born at home, both passed meconium before birth. When expecting her third baby she had firm views on whether this would affect her homebirth plans or not.
Deb's third baby, Jude, had stale meconium in his waters. He was born safe and well just a few minutes after the waters broke.
Sally was planning a homebirth after a previous caesarean when her baby passed thick meconium. Sally transferred to hospital because she knew that things were not right. Her labour did not progress and she had a repeat caesarean, but Emilio had Meconium Aspiration Syndrome and had to spend time in Special Care.
Victoria's baby Jocelyn passed meconium as she was born (often it is passed immediately afterwards as well). Victoria wrote that "Normally we would have been asked to go into hospital for her to be checked because she'd passed meconium, but the midwife phoned the hospital and spoke to the registrar who agreed that it wasn't necessary (I think he heard her in the background and figured her lungs were alright!)"
Alex gave birth to first baby Nathan in hospital after transferring because meconium was found in the waters. His heart rate showed no sign of distress, and he was 11 days postdates so the midwife said the meconium was probably caused by his being overdue.
Tric saw meconium when her waters went in the birth pool, but her midwife was not worried because the baby's birth was imminent, and baby Caoimhe was fine.
Home births when meconium is present - discussions in the US Midwife Archives (www.gentlebirth.org).
Meconium Aspiration - detailed info and references from www.patient.co.uk.
I've searched on Medline and the reviews published since Lesley Page's book was written seem to support her findings - especially that intubation and deep suctioning is not necessary unless the baby is depressed at birth, and that meconium in the absence of other signs of distress doesn't seem to be a big issue. I've copied below another abstract which looks interesting, on the question of mec in pre-dates and post-dates babies - Ahanya et al (2005) - as well as the references cited above.
Am J Obstet Gynecol. 1992 Jan;166(1 Pt 1):171-83.
Am J Obstet Gynecol. 1992 Dec;167(6):1914-6.
Meconium aspiration syndrome: reflections on a murky subject.
Katz VL, Bowes WA Jr.
Department of Obstetrics and Gynecology, University of North Carolina, Chapel Hill 27599-7570.
Meconium-stained amniotic fluid occurs in approximately 12% of live
births. In approximately one third of these infants meconium is
present below the vocal cords. However, meconium aspiration syndrome
develops in only 2 of every 1000 live-born infants. Ninety-five
percent of infants with inhaled meconium clear the lungs
Recent investigations have suggested that a reexamination of our assumptions about the etiology of meconium aspiration syndrome is in order.
Several authors have provided evidence that support the hypothesis that it is not the inhaled meconium which produces the primary pathologic condition of meconium aspiration syndrome but rather it is fetal asphyxia that is the etiologic agent. Asphyxia in utero produces pulmonary vasospasm and hyperreactivity of the pulmonary vessels. With severe asphyxia the fetal lungs undergo pulmonary vascular damage with pulmonary hypertension. The damaged lungs are then unable to clear the meconium.
In the most severe cases there is right-to-left shunting and persistent fetal circulation with subsequent fetal death. The incidence of meconium aspiration may thus be essentially unaffected by current obstetric and pediatric interventions at birth.
For the asphyxiated or distressed infant we recommend suctioning at birth and tracheal intubation. In the healthy fetus observation may be sufficient.
PMID: 1733193 [PubMed - indexed for MEDLINE]
Obstet Gynecol Surv. 2005 Jan;60(1):45-56; quiz 73-4.
Meconium passage in utero: mechanisms, consequences, and management.
Ahanya SN, Lakshmanan J, Morgan BL, Ross MG.
Department of OB/GYN, Harbor UCLA Medical Center, David Geffen School of Medicine at UCLA, Torrance, California 90509, USA.
Meconium passage in newborn infants is a developmentally programmed
event normally occurring within the first 24 to 48 hours after birth.
Intrauterine meconium passage in near-term or term fetuses has been associated with fetomaternal stress factors and/or infection, whereas meconium passage in postterm pregnancies has been attributed to gastrointestinal maturation.
Despite these clinical impressions, little information is available on the mechanism(s) underlying the normal meconium passage that occurs immediately after birth or during the intrauterine period of fetal development. Birth itself is a stressful process and it is possible that fetal stress-mediated biochemical events may regulate the meconium passage occurring either during labor or after birth. Aspiration of meconium during intrauterine life may result in or contribute to meconium aspiration syndrome (MAS), representing a continued leading cause of perinatal death. This article reviews aspects of meconium passage in utero, its consequences, and management.
PMID: 15618919 [PubMed - indexed for MEDLINE]
'Meconium-stained amniotic fluid' by McNiven, Roch and Wall, a review published in 'Modern Midwife', July 1994.
This page updated 26 August 2006