Reviewer’s report
Title: 
Comparison of levonorgestrel level and creamatocrit in milk following
immediate vs. delayed postpartum placement of the levonorgestrel IUD
Version: 
1 
Date: 
07 Nov 2020
Reviewer's report:
Thank you for your revisions.
Page 4- "However, this assay is yet to be formally tested in human milk samples
in a comparative 67 clinical trial assessing variable timing of hormonal
exposure." 
Please add a sentence explaining where this new test has been
validated - is it valid for serum only at this point? 
Any comment, if true, that the
assay would be expected to perform as well for testing of human milk, or that
there is promising pilot data on its validity for human milk testing would also be
appropriate. There is a gap here that leaves readers wondering how useful the
test actually is for human milk.
Page 4 - Please revise this sentence for grammar and understandability: "While
human milk creamatocrit has prospectively evaluated in 1,322 exclusively
breastfed infants contraceptive exposure was not reported."
Page 4 - In the sentence that follows, give readers a brief summary of the results
of this study: "However, in a much smaller study creamatocrit at 6 weeks was
reported in contraceptive implant users." The word "however" might best be
removed from this sentence and added to the beginning of the sentence that
follows.
Page 4 - The key sentence that starts, "The purpose of this study…" fails to
deliver the purpose. Consider adding the phrase in brackets and revising from
"of" to "between." 
"The purpose of this study is to assess the role of timing of
levonorgestrel IUD placement 86 in postpartum outcomes by comparing [the
levonorgestrel and crematocrit concentrations of] milk samples of [between]
women randomly assigned to immediate (less than 30 minutes) postpartum
levonorgestrel IUD insertion to those with delayed (4-8 week) insertion." 
Page 7- The details of managing the informed consent could be omitted ("When
we completed substudy enrollment…"). 
In the sentence that follows please
remove the clause "This aspect of the consent form" which must have been
mistakenly not previously erased.
Discussion
An additional key limitation to at least note is that milk volumes per mother were
not measured, since one stated concern about hormonal contraception with
progesterone is its possible impact on milk production.
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