This is based on an email I sent in response to a query on the Homebirth UK email group from a woman who had been told that she should not have a homebirth because her baby's head was not engaged.
This page is a rough draft. If any midwives or mothers have comments, I'd be very grateful if you could let me know by emailing angela @ homebirth.org.uk.
Please note that I am not a health professional; my aim is to direct you to information and case studies to help you make your own decisions.
It's much more common for second and subsequent babies not to engage until you go into labour, than it is for first babies.
I'm assuming that your baby's head is free-floating, or high in your pelvis, rather than 'dipping' into your pelvis or partially engaged. It's important to be clear on this as some people talk about 'not engaged' meaning 'not fully engaged' whereas nowadays it is more common if your midwife says the baby is 'not engaged' to mean 'not engaged at all'.
For a first-time baby it is actually quite unusual for the baby to be fully engaged (ie this would be written 0/5 or 1/5 palpable, or "deeply engaged", "4/5 or 5/5 engaged" on your notes) ; most will be something like 3/5 palpable (ie 2/5 of the head engaged in the pelvis) or 4/5 or whatever. Some midwives write this in a slightly different way - they will write down the amount of the head which cannot be felt, ie the amount which is below your pelvic brim, so "3/5 palpable" means that 2/5 has engaged and cannot be felt, etc..
Mayes Midwifery textbook cites the classic study on this, Weekes & Flynn (1975) which found that:
"..in 50 per cent of patients, engagement occurred between 38 and 42 weeks .. These findings strongly suggest that in the majority of primigravid patients the fetal head does not engage between 36 and 38 weeks of gestation (252 to 266 days) as is commonly believed."
OK, so what does it mean if the head is high at term, for your first baby? Well, if the head is still free-floating when you go into labour, then you do have a higher chance of ending up with a caesarean for slow progress. HOWEVER, the vast majority of women whose first babies are completely unengaged when they go into labour, will still have a vaginal birth.
See for instance Murphy, Shah and Cohen (1998) (see refs) who found, among women presenting in spontaneous labour, that 27% with free-floating fetal heads ended up with a c-section, compared to just under 7% of those whose babies' heads were engaged or dipping at the start of labour. I have to say that their overall c-section rates seem very impressive for a US hospital. Similarly impressive results were found by Debby et al (2003), for whom 17.1% of first-time mothers with floating fetal heads had a c-section, compared to 4.2% of those with engaged fetal heads. They concluded:
"Nulliparous women presenting in active labor at term with a floating head are at substantially increased risk of cesarean section for abnormal progress of labor. However, the majority of patients will still deliver vaginally. A persistently floating head with advanced cervical dilation (7 cm) should prompt consideration of cesarean section since little is to be gained by waiting. "
SO.... it's certainly not the case that, if your baby's head is still free-floating when you go into labour, then a c-section is inevitable.
Bear in mind also that most studies on high heads and CS rates have looked at first-time mums; if you've already given birth vaginally then your risk of ending up with a CS will be much lower.
The worry about a high head at a homebirth is that there is a theoretically higher chance of a prolapsed cord, if the waters break with a gush while the head is still high. The cord could be washed down, and get pushed in front of the baby's head. If the head then descends suddenly, because its cushion of waters has gone, then the cord could be compressed between the head and your pelvis. This is life-threatening for the baby wherever it happens, and you would need an urgent caesarean ASAP.
The biggest risk of cord prolapse is in situations where there is a very unsual presentation, like breech or transverse, and in multiple pregnancies and premature labours. It's also riskier where there is an unusually high volume of amniotic fluid (called "hydramnios" or, formerly, "polyhydramnios"), and it's very common to have a high head with hydramnios too.
Here's some research on cord prolapse - from an excellent article on the topic aimed at obstetricians, in Contemporary Ob-Gyn: www.contemporaryobgyn.net/obgyn/article/articleDetail.jsp?id=184602&&pageID=2"In a study conducted by Roberts and associates, for instance, induction of labor, cervical ripening, amnioinfusion, and amniotomy did not increase the risk of umbilical cord prolapse; but there was a link with higher fetal station at the time of umbilical cord prolapse. There was no difference in the incidence of umbilical cord prolapse among those patients who underwent amniotomy compared to spontaneous membrane rupture. "
That last sentence relates to the theory that cord prolapse is more likely if your waters are broken (amniotomy) than if they break on their own; the idea is that waters breaking naturally tend to do so during a contraction, and the contraction will be pushing the baby's head down firmly while the waters break, so there would be less room for the cord to be washed down in front of the head. Whereas if your membranes are artificially ruptured (ARM), this would normally be too uncomfortable and difficult to do during a contraction, so there would be more room for cord prolapse to occur. It's very hard to test this theory and the fact that one study didn't find any correlation doesn't really prove the issue - cord prolapse is so rare that it's hard to find a large enough study group.
Looking at the abstract of that study (copied below), what they say is that the issue regarding fetal station (ie how high the head is) is not how high it is at the start of labour, but whether it descends as your labour progresses. It says there wasn't a significant difference between head station on admission to hospital in the cord prolapse study group and the control group.
I've found a few other studies and none of them seem to identify a high head ('high station') as a statistically significant risk factor on its own. The risk factors mentioned are those I've listed above. I've only looked at the abstracts though, not the full studies. It's possible that this is identified as a minor risk factor somewhere in the full text, which I don't have access to.
So the upshot of this is - if you start off at home with a high head, and your labour doesn't show good signs of progress with the head moving down, then yes, you are certainly at some increased risk, both of cord prolapse and of ending up with a caesarean for lack of progress. These are very different risks though - a cord prolapse is a critical emergency whereas a CS for slow progress is a decision you come to after you've been waiting, and going nowhere, and decide that you've had enough.
But if you start off at home and your labour progresses well - then it's not clear how much, if at all, your risk is increased.
Do all you can to encourage baby into a good position - see Get Your Baby Lined Up for more on optimal foetal positioning. It's helpful to work out for yourself how to tell which way your baby is lying, so that when you are sure he's in a good position (LOA) you can then try to keep him there - lots of breaststroke swimming, as the leg movement is thought to encourage engagement, and keep upright and forward-leaning when you go into labour. Some midwives recommend binding your abdomen to encourage baby to move down, but again you only want to do this if you're happy with his position as you don't want him to engage in the OP position.
There are a couple of birth stories on this site where a high head has been an issue - relevant bits extracted below:-
==============From Sidney's birth story, by Jeanette Archer
I was reluctant to have another exam as I felt the baby was bobbing out of my pelvis when I lay down, but was right in it when stood up.
We finally agreed to do another exam, and see what if anything was happening. So I endured another incredibly painful exam, and as predicted, no progress, the head was still high enough that if the bulging membranes were ruptured there was a risk the cord might come down first!
BUT, there was hope! The mw took on board what I had said about the head bobbing out and she propped me up with as many cushions as she could find.hey presto! The head was far down enough to break the waters, which she did.what a relief!
==========================
Oscar's birth story, by Brigett
(Oscar is Brigett's first baby)
There I was, hugely pregnant with a baby that was due 5 December and on 24 December still no showed no sign that he was on his way. My daily visit to the hospital still showed our baby to be in perfect health. The head wasn't engaged and nor was my cervix effacing as much as might be expected. I underwent a cervical stretch and sweep on Christmas eve and couldn't believe Christmas day was almost here! He was 19 days overdue.
(Brigett's waters went with a whoosh the next day and Oscar engaged fully and was born at home).
Prolapsed Cord - from patient.co.uk, the NHS patient information database.
http://www.patient.co.uk/showdoc/40000243/
World Health Organization guidelines on emergency management of cord prolapse
(www.who.int/reproductive-health/impac/Symptoms/Prolapsed_cord_S97_S98.html)
Here is one tragic case report of a cord prolapse occurring at home. After the midwife detected the prolapse, the mother transferred to hospital with the midwife manually holding the baby's head up off the cord. It took 56 minutes from the detection of the prolapse to the caesarean delivery of the baby, who died three days later. The mother, Traci Relph, is a midwife herself and in this Daily Telegraph article she explains why she still supports home births. She feels that the outcome would still have been bad if she had been in hospital when the prolapse was detected, as her son might have still died, or might have lived but been severely disabled. She would certainly have had the c-section much faster if she had been in hospital; in a case this urgent, most hospitals would be able to deliver the baby within 30 minutes.
Br J Obstet Gynaecol. 1975 Jan;82(1):7-11.
Engagement of the fetal head in primigravidae and its relationship to
duration of gestation and time of onset of labour.
Weekes AR, Flynn MJ.
In a retrospective survey on the time of engagement of the fetal head in 462 unselected consecutive primigravidae it was seen that by the end of the 37th week of gestation (259 days), engagement had occurred in only 23 per cent of them. The highest rate of engagement was from 39 to 40 weeks of gestation (273 to 280 days) and in 50 per cent of patients, engagement occurred between 38 and 42 weeks (266 to 294 days). The mean interval between engagement and delivery was 1.39 weeks (9.7 days), the median was 7 days, and the mode was less than 7 days. In 80 per cent of patients the engagement-delivery interval was less than 14 days. These findings strongly suggest that in the majority of primigravid patients the fetal head does not engage between 36 and 38 weeks of gestation (252 to 266 days) as is commonly believed.
PMID: 1138823 [PubMed - indexed for MEDLINE]
J Perinatol. 1998 Mar-Apr;18(2):122-5.
Labor and delivery in nulliparous women who present with an unengaged
fetal head.
Murphy K, Shah L, Cohen WR.
Department of Obstetrics and Gynecology, Albert Einstein College of
Medicine, New York, NY, USA.
OBJECTIVE: We assessed the relation of fetal station in early labor to subsequent patterns of dilation and descent and to the probability of cesarean delivery.
STUDY DESIGN: We evaluated 132 nulliparous women who were in spontaneous latent-phase labor with singleton, vertex-presenting, term fetuses. For each participant, pertinent variables relating to labor characteristics and mode of delivery and newborn characteristics were recorded. Labor curves were drawn and analyzed.
RESULTS: Of the 132 participants, 29 (22%) presented with an engaged fetal head, and 103 (78%) presented with an unengaged fetal head. In the unengaged group, 15 (11%) presented with a floating fetal head (-3 station or above), and 88 (67%) presented with a dipping fetal head (-2 or -1 station). A floating head in latent-phase labor conferred a longer second stage (p = 0.02), a trend to more active-phase labor disorders (p = 0.06), and a greater risk of cesarean delivery. Overall, 12 patients (9%) underwent primary cesarean section: 2 (6.9%) from the engaged group, 6 (6.8%) from the dipping group, and 4 (27%) from the floating group (p = 0.042).
CONCLUSION: Most nulliparous women in this study presented in labor with an unengaged fetal head. Those with a floating fetal head demonstrated higher rates of cesarean section than those with dipping or engaged heads in early labor.
PMID: 9605302 [PubMed - indexed for MEDLINE]
J Reprod Med. 2003 Jan;48(1):37-40.
Clinical significance of the floating fetal head in nulliparous women in labor.
Debby A, Rotmensch S, Girtler O, Sadan O, Golan A, Glezerman M.
Department of Obstetrics and Gynecology, Edith Wolfson Medical Center,
Holon, and Sackler School of Medicine, Tel Aviv University, Tel Aviv,
Israel.
OBJECTIVE: To examine the course of labor in nulliparous women in
active labor with a floating fetal head.
STUDY DESIGN: A prospective, cohort study of nulliparous women
presenting in active labor at term with a floating fetal head (station
> or = -3, n = 108) or engaged fetal head (n = 241). All patients were
examined by a senior physician. Assignment to the study or control
group was noted in the investigator's records. However, management of
labor was at the discretion of the labor ward team on duty.
RESULTS: Cesarean section rates for failure to progress were significantly higher in the study group ( 17.1% versus 4.2%, P < .0001), and the second stage of labor was prolonged (65.3 +/- 27.1 versus 54.9 +/- 30.2 minutes, P < .03). None of the women who had a persistently floating fetal head at 7 cm of cervical dilation delivered vaginally. Birth weights were larger (P < .03) and Apgar scores lower (P < .0001) in the study group. The lengths of the active phase and instrumental delivery rates were similar in the two groups.
CONCLUSION: Nulliparous women presenting in active labor at term with a floating head are at substantially increased risk of cesarean section for abnormal progress of labor. However, the majority of patients will still deliver vaginally. A persistently floating head with advanced cervical dilation (7 cm) should prompt consideration of cesarean section since little is to be gained by waiting.
PMID: 12611093 [PubMed - indexed for MEDLINE]
Am J Obstet Gynecol. 1997 Jun;176(6):1181-3; discussion 1183-5.
Are obstetric interventions such as cervical ripening, induction of
labor, amnioinfusion, or amniotomy associated with umbilical cord
prolapse?
Roberts WE, Martin RW, Roach HH, Perry KG Jr, Martin JN Jr, Morrison JC.
Department of Obstetrics and Gynecology, University of Mississippi
Medical Center, USA.
OBJECTIVE: Our purpose was to determine whether intrapartum obstetric interventions are associated with umbilical cord prolapse.
STUDY DESIGN: A computer search identified patients who had intrapartum umbilical cord prolapse. Thirty-seven cases were identified between 1990 and 1994 (incidence of 1.85 per 1000). These women were randomly matched to control patients with intact membranes.
RESULTS: Patients with umbilical cord prolapse were delivered earlier (34.8 vs 37.1 weeks, p = 0.05). Otherwise, there were no differences between groups regarding the use of cervical ripening, incidence of labor induction, or the use of amnioinfusion and amniotomy. Although cervical dilatation and station were similar between groups at the time of admission, women with umbilical cord prolapse did not have as much descent of the presenting part associated with cervical dilatation and progressive labor compared with control patients.
CONCLUSION: By themselves, obstetric interventions of cervical ripening, labor induction, amnioinfusion, and amniotomy do not increase the likelihood that a patient will have umbilical cord prolapse.
PMID: 9215171 [PubMed - indexed for MEDLINE]
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