Dolichocephaly – understanding ‘breech head’ molding

This post is about dolichocephaly, a form of positional molding which affects some breech babies – how it happens, why it may be important, and how to recognise it.

Everyone is concerned about entrapment of the after coming head in a breech birth. And it seems so unpredictable. Many breech babies, even large ones, seem to just fall out. And then others, not so large, get stuck. RCOG guidelines suggest an estimated fetal weight above 3800 g is ‘unfavourable’ for vaginal breech birth, but goes on to say, “If the baby’s trunk and thighs pass easily through the pelvis simultaneously, cephalopelvic disproportion is unlikely.” (Easily is undefined, but in light of the evidence against augmenting breech labours, I interpret it as occurring spontaneously within about an hour of active pushing.)

Can we predict which babies’ heads are more likely to have difficulty passing through the pelvis? I don’t know, but I feel one phenomenon in particular deserves more attention – dolichocephaly.

Dolichocephaly developing due to positional pressures

Dolichocephaly developing due to positional pressures

Technically, dolichocephaly is a mild cranial deformity in which the head has become disproportionately long and narrow, due to mechanical forces associated with breech positioning in utero (Kasby & Poll 1982, Bronfin 2001Lubusky et al 2007). This change in shape is more commonly associated with primiparity (first babies), larger babies, oligohydramnios, and posterior placentas, all of which result in greater forces applied to the fetal head.

(Note: Like all positional molding which occurs in utero, dolichocephaly does not in itself cause nor indicate abnormal brain development. The head shape is highly likely to return to completely normal in the days and weeks following birth, especially if baby receives lots of holding and cuddles to permit free movement of the head.)

Clinical Importance

Following the birth of the arms in a breech birth, the head will be in the anterior-posterior diameter of the pelvis. When the head shape has become abnormally elongated, the longest diameter of the fetal head will meet the shortest diameter of the maternal pelvis at the inlet. Unless the baby is still on the small side and the pelvic inlet very round, the chin may get stuck on the sacral promontory, preventing head flexion. A very experienced breech provider will have encountered this situation before, and should be able to assist, but it is quite a tricky place to be. The head may need to be rotated into the transverse diameter to safely enter the pelvis. A very elongated head can have difficulty passing through the lower pelvis as well, and can cause damage to the maternal pelvic floor, unless appropriate techniques are used to assist the head to flex.

Effects of abnormal head molding in some breech-positioned babies

Abnormal head molding in some breech babies

Estimation of fetal weight by ultrasound is notoriously inaccurate. However, a lack of proportionality between the head circumference and the biparietal diameter is more obvious to spot (e.g. HC=90th percentile, BPD=60th percentile; or a difference in correlating dates of two weeks or more), and may be a more relevant indication that this baby is too big for this particular woman. Dolichocephaly can be discerned on palpation as well, as the occiput is prominently felt above the fetal back, the head is not ballotable, and may feel unusually wide. I would suggest caution where estimated fetal weight is above 3500 g and a difference in HC and BPD, or careful palpation, indicates abnormal cranial molding has occurred, especially for women who are having their first baby, have a low amniotic fluid index, and/or a high posterior placenta; and in situations where imaging pelvimetry is not used to confirm an ample pelvic inlet.

Counselling Women

Women instinctively do not like weight limits used as ‘selection criteria.’ One woman (Ann, multip, 6’1”) looks at another (Carol, primip, 5’0”) and they both think – We can’t possibly be expected to have similar-sized babies. While Ann may carry a 4000 g baby with no abnormal head molding, and expect a straightforward birth, Carol’s baby may begin to show signs of dolichocephaly at 3300 g, especially if she has low levels of amniotic fluid and a posterior placenta. Carol may still have a successful birth, but it will more likely depend on the skill and experience of her attendant in assisting the aftercoming head to flex, rotate and negotiate the pelvic diameters, and the pelvic diameters themselves.

A 'normal' breech baby - well-flexed, with lots of room to move

A ‘normal’ breech baby – well-flexed, with lots of room to move

We need to move away from the concept of ‘selection criteria,’ which are used by professionals to make decisions for women, and towards an understanding of what is ‘normal for breech.’ We need to understand more about which babies are more likely to experience those beautiful, often-easier-than-cephalic, dancing-into-the-world births, and which babies are truly being put at additional risk by their in utero conditions.

Then we will be able to explain to women the benefits of a caesarean section for pregnancies which have become ‘abnormal.’ Women will be able to approach this intervention with an open heart when they observe professionals are truly supporting ‘normal’ breech births and providing individualised care and screening to those which are not.

I would love to know what others think about this.

Shawn

23 thoughts on “Dolichocephaly – understanding ‘breech head’ molding

  1. Elly

    Enjoyed reading . Makes sense . Am now thinking what are the skills I need as an attendant and how to know which way to turn baby if chin is wedged on coccyx .also palpations I find hard sometimes .

    Reply
    1. midwifeshawn

      Indeed! I am still working on that one myself. Palpation will come with practice. Keep a self-audit of weights and positions. Give yourself permission to not be right all of the time. 75% of babies referred to my clinic for ?breech were cephalic on USS, and 30% of all breeches are missed. Clinical skills and technology should back each other up.

      Reply
  2. Joy Horner

    Once again you’ve clearly highlighted the importance of useful selection criteria rather than blanket rules, and asessing each case as unique . I’ve assisted a primip birth a 4.2 kilo baby with relative ease and had a primip with a much smaller baby get stuck at the sacral promontory. The flattened top to the baby’s head over the anterior fontanelle region is commonly seen after breech birth and may well increase the AP diameter. Thank you again for adding further knowledge to the breech birth arena. X

    Reply
    1. midwifeshawn

      Yes, great point Carly. Another midwife said this to me recently .. if it had not been for the scan, she would have thought it was a bum. To me, already knowing it was breech, it felt like an abnormally elongated head, sitting in transverse (and was).

      Reply
  3. Jacque Gerrard

    This is brilliant Shawn. I had forgotten the term Dolichocephaly because I have not seen it for years due to lack of vaginal breech births.We need to share wider to inform students and recently qualified midwives! Well done on the great breech work. Jacque

    Reply
  4. De Vries

    I always say: the fat is on the bottom, not on the head. So a small baby has more risk to get stuck with the head than a bigger baby in breech position. If the baby is bigger, the head is not the bigger part, but the bottom is.

    Reply
    1. midwifeshawn

      Thank you for this, Janke.

      I agree that when bigger babies fit through a pelvis, it stands to reason their heads will, and of course a bigger baby will be more resilient in the case of a delay. However, as with a cephalic baby, fitting through the pelvis easily requires the head to be in an ideal position. I feel a misshapen head which becomes deflexed in cases of fetal compromise may have more potential to become caught at some stage in the birth process, and therefore become dependent on the birth attendant to help the head into a more ideal, flexed position to navigate the pelvis. But it’s just a theory!

      If you have experience attending breech births, I would love for you to consider participating in my research!

      Shawn

      Reply
  5. Lisa

    Only just seen this!!!! May explain an issue I had with a recent birth where the head didn’t engage at the same speed in previous births I’d attended. Baby did indeed have dolicocephaly and am now wondering if that was the issue rather than primiparity & syntocinon (I know, don’t even get me started on the synto part :-{). Issue resolved with turning to lithotomy & Mauriceau. All ended well (parents ecstatic) but this might well explain the delay 😉

    Reply
    1. midwifeshawn

      Thanks for sharing that experience, Lisa. Would love to hear more about 1) how you diagnosed that the head had not engaged, eg. what you felt; and 2) whether you feel the change in position assisted the engagement at all. If it was not possible to perform Mauriceau with the woman upright, did it feel more possible after turning to lithotomy? 🙂

      Reply
    1. midwifeshawn

      Hi, Alan. My thoughts around dolichocephaly end at birth. A paediatrician would be best placed to advise you on the consequences of childhood dolichocephaly. A cranial osteopath would probably have some thoughts as well. Best wishes, Shawn

      Reply
  6. David

    My head is long I’m african too but I wanted to know how I can get it smaller if it’s possible. Does anyone have answers please ??

    Reply

What are your thoughts?