Review for 10.1186/1471-230X-11-6 (2011)

Reviewer's report
Title:Effect of the mode of delivery on Crohn's disease; results from a
retrospective cohort study
Version: 1Date:23 June 2010
Reviewer: Louise C. Kenny
Reviewer's report:
This is a retrospective cohort study, which sets out to examine the effect of
pregnancy on subsequently disease progression in women of reproductive age
with Crohn’s disease. There is a paucity of research in this topic for reasons
outlined by the authors, which I concur with, and therefore there is unlikely to be
an RCT in this area. This is therefore an important topic and one in which a well
designed retrospective study may add significant value.
Major Compulsory Revisions:
1. The study population is derived from an inflammatory bowel patient database
at a tertiary hospital. All women of reproductive age on the database in 2004
were selected. It’s not clear why this year was selected. Do the authors believe
that 5 years is needed to assess disease progression following delivery? They
have restricted disease progression to within 2 years of delivery of the index
pregnancy. Why then did they not select a later year when perhaps more of the
‘voluntary childless’ women may have conceived thus increasing the power of the
study? Was this study performed some time ago? Further details are required.
2. A fundamental flaw of this study is the reliance on patient recall with regard to
the obstetric data. Obstetric charts were not reviewed as patients delivered in
more than one obstetric unit. Whilst it does not invalidate the entire study, it
significantly reduces the strength of the information particularly with regard to
pregnancy complications. For example, no information is given as to the
definition of fetal growth restriction. This is a pathological process- not merely the
presence of small for gestational age or low birth weight babies. This needs to be
dealt with in the text or perhaps removed from the paper.
3. Many clinicians would argue that the reason abdominal delivery is
recommended in women with perineal disease, particularly nulliparous women is
because of the possibility of significant trauma which will then be slow to heal.
Certainly an uncomplicated vaginal delivery with no perineal trauma would be
considered the best outcome even in women with active perineal disease but the
high possibility of an instrumental vaginal delivery and/or an episiotomy or
spontaneous tears in a primiparous population deters clinicians from offering this
choice. I think it is important therefore for the authors to include information on
the mode of vaginal delivery (spontaneous or instrumental). This is information
that should be readily obtainable even in a study relying on patient recall.
4. I note that this study was performed in the Netherlands. Traditionally the
Netherlands have very low instrumental vaginal delivery rates and C-section
rates compared with other countries. I think the discussion should include
mention of the fact that this means it is difficult to extrapolate the findings of this
study to other healthcare settings. This is particularly so when we do not know
the definition of ‘medical advice’ versus ‘obstetric reasons’ for C-section delivery.
Level of interest: An article whose findings are important to those with closely
related research interests
Quality of written English: Needs some language corrections before being
published
Statistical review: Yes, but I do not feel adequately qualified to assess the
statistics.
Declaration of competing interests:
I declare that I have no competing interests