Reviewer's report
Title:Maternal hair selenium levels and recurrent pregnancy loss.
Version: 1Date:2 December 2012
Reviewer: Uchenna Nwagha
Reviewer's report:
Major compulsory revisions
1. Methods.
a. The Control subjects were healthy, non-pregnant women with at least one
living child who had not been pregnant during the last 6 months, while the
patients have had recurrent miscarriage. What was the interval between the last
miscarriage and the time of study? This is extremely important as what is
essential is the selenium status around the time of the miscarriage.
b. The inclusion and exclusion criteria were not clearly stated.
c. How did the authors avoid selection bias and how was the sample size
determined and why?
d. There was a significantly higher household income among control subjects,
indicating that the two groups differed significantly in social class and thus were
not properly matched. It is essential in nutritional studies for subjects to be
matched socioeconomically.
e. The dietary questionnaire did not include the period covered (24hour, one
week, one month or more).
f. There was no evidence of the time interval between the last hair treatment and
sample collection.
g. There was no statement regarding data presentation (descriptive and
inferential statistics, including the reason for adopting Man Whitney U for
statistical significance.
The percentage composition of selenium in the body varies from tissue to tissue
Approximately 30 percent of tissue selenium is contained in the liver, 15 percent
in kidney, 30 percent in muscle, and 10 percent in blood plasma. For the authors
to make a definitive inference, the serum selenium level during/around the time
of the miscarriages should be provided. Using hair selenium months after a
miscarriage to retrospectively determine the relationship between selenium and
RPL presents a serious methodological flaw. Selenium deficiency may cause
oxidative stress, induce damage to DNA and cause miscarriage. Also, impaired
growth and development as well inability to prohibit certain infection may
aggravate the scenario. Thus, the serum selenium level around the time of the
miscarriage would have been more appropriate if the authors must assume that
there is no connection between selenium and RPL. The study would have made
some meaning if serum selenium was determined at the same period of
estimating hair selenium to determine any correlation between the two. Even at
that, collecting the samples at/around the time of the miscarriage would have
been perfect. Furthermore, identifying pre pregnant women with low selenium,
and following them through pregnancy should have been the standard. Finding
that hair selenium concentrations and dietary selenium intake, were similar in the
two groups is grossly inadequate to conclude that selenium is not implicated in
RPL.
2. Discussion: The discussion was not properly written as the authors simply
stated their findings, compared them with similar studies, and attempted to
proffer the likely explanation for the results.
Authors should clearly state the following:
a. State the implications of their findings to medical practice as it concerns
Selenium and RPL.
b. The major strengths and perceived weaknesses of the study design.
c. What are the avenues and prospects for further research?
Level of interest: An article of importance in its field
Quality of written English: Needs some language corrections before being
published
Statistical review: No, the manuscript does not need to be seen by a
statistician.
Declaration of competing interests:
'I declare that I have no competing interests'