PREreview of The Pattern of Changes in Body Mass Index before and during Pregnancy: The Maternal and Neonatal Outcome

Thank you authors for this valuable study.

Sayed et al investigated the pattern of gestational weight gain during pregnancy and how it may affect maternal and neonatal outcomes. The authors chose to utilize the BMI in the comparisons. Although the issue is not novel, but this study is distinct by that it involved multiple weight categories by BMI and multiple maternal as well as neonatal outcomes. This is unlike many of the previous studies, which makes this study a big one that requires much rigorous evidence generation and analysis.

The Major Fkaws:

a.       Title:  The title is attractive. But the word 'before' would cause confusion. The title without the word ‘before’ promptly conveys just the exact and true objective of the study.

b.      In the Abstract: A Serious discrepancy is evident: in the results description the statement:” The study sample included 2,352 natives (25%) and 7,058 expatriates (75%). Most of the sample (4726) were…etc” seems alien as later in the main body and throughout to conclusion the study describes a study data of only 2960 women.

c.       Methods: The method and study design is not clearly and explicitly mentioned and detailed first thing at the beginning of this section.

Inclusion criteria and (more importantly) exclusion criteria not explained distinctly. Also time frame of the study was not specified.

Definition of terms of variables and outcomes were not provided, and consistent use of the same terms in describing variables, outcomes and categories especially when doing statistical analysis was not maintained..

d.      Limitations of the study were not recognized/mentioned although the authors provided the strength points. Limitations should be duly reported including the secondary data limitations, the single- facility, and the exclusion of the private sector. Moreover the selectivity of certain outcomes an leaving others such as preeclampsia, birth defects.

2. General remarks:

• Divide lengthy chunks of text into shorter paragraphs (particularly in the Methods section) according to context for better readability.

• Use abbreviations consistently: After defining an abbreviation at its first occurrence followed by the abbreviation in parenthesis, continue using the abbreviation alone throughout unless you (optionally) wish to put the full term in the tables and figures.

• Use % mark instead of 'percent'

• Use square brackets ‘[ ]’ for in-text citation. instead of parenthesis ‘( )’

• An expert statistician may be needed to comment, as the complex nature of the study would possibly entail extra/ other statistical approaches.

Other observations in sequential order (some are important)

 1.      In Abstract: Background::

• Too short, authors may wish to add another one/couple of informative input.

2.      In Abstract: abbreviations (BMI NICU CS PPH)

• If authors chose to keep abbreviations in the Abstract, they should spell out the full term at first occurrence then follow by the abbreviation.

3.      Methods:

• Divide the one-block text into smaller paragraphs distinctly describing elements of methodology (define the method clearly, then type and source of data, collection tool, define eligibility (inclusion/exclusion criteria). In a separate paragraph mention the ethical consent declarations

4.      First sentence in Methods: “This study used data…funding the registry (QNRF).”

• Rephrase to be understandable

5.      Last sentence in Methods: “The current study looked at the BMI… time of birth.”

• Move this sentence up. This should be among the first statements in this section.

6.      Statement in Methods: ” The BMI of everyone was computed … height (centimeter)”

• not the exact right formula: (in meters squared). Better to write down the equation for clarity

7.      Statement in Methods: ” The following BMI categories … and (4) "obesity."

• Authors should provide distinct definition of each category according to their BMI range & mention the guidelines followed in classifying (e.g. WHO, )

8.      ‘Outcome metrics’:

• differentiate variables from outcomes and include all studied factors

9.      In ‘Outcome metrics’: “Neonatal variables included low birth weight… NICU”

• Also high birth weight “LGA” (>4000grams)

10.  In ‘Outcome metrics’; “gestational age less than 37 weeks,”

• Do you mean ‘preterm’?

11.  In results: “single pregnant women”

• To avoid confusion with any other meaning, better change to “single pregnancy women”

12.  Sentence in results: “The pre-pregnancy BMI was calculated to be 2,960”

• Not clear kindly explain or remove

13.  Sentence in Results: “2.8% (83) of women were underweight”

• Rephrase to avoid putting number at the beginning

14.  Sentence in Results: “Increased BMI increases the risk of cesarean... hypertension”

• Authors may wish to express as e.g: “Increased BMI showed association with increased risk of cesarean... hypertension”

15.   Sentence in Results: “An above-normal BMI, on the other hand..etc”

• Kindly mention explicitly which category(s) of BMI you meant.

16.  Sentence in Results: “.and two times more likely to have hypertensive issues.”

• Clarify, what issues?

17.  Remark under Table 1: “ ** 19-year group had no underweight”

• The remark is not needed, as it is clearly indicated in the table as 0(0%)

18.  Table 2:

• Enter a definition for the first column. Write categories in full e.g. ‘underweight’ not ‘under’.

19.  In Table 2: the last row of first column: “All types of DM”

• Kindly explain what it is, and clarify why this outcome was not originally included in the method section above.

20.  In Table 3: the last row first column: “LR/OT”

• Write abbreviation in full or define under the table

21.  In Figure 1:

• Add number of patients to the 40-50yrs group

22.  In Figure 2: ‘Pre-gestation BMI*”

• Unexplained appearance of a non defined class of BMI without prior elaboration in methods. Kindly provide enough explanation before presenting in the table

What is the difference between “Pre-gestation” and “Pre-pregnancy BMI”?

23.  In ‘The study's advantages’; “The study cohort's prospective nature”

• The study is a retrospective one as described by the authors and evident by design. How prospective??

24.  In ‘The study's advantages’:”because of the large size of the cohort..”

• Although sample size is not too small but projecting as characteristically large may not be a solid claim. Looking at studies in reference [17] of this manuscript, where the largest sample size was (560,000) with average sample size of about (57,000) will show that only 7 out of 23 studies included a sample size smaller than the present study.

25.  In ‘The study's advantages’: ” conducting the study in a single institution”

• The single health facility is mostly on the side of limitation to any study.

26.  In ‘The study's advantages’; “the study population and sample are distinct”

• Not clear, kindly explain

27.  In the ‘List of Abbreviations’ : “HMC”

• This abbreviation was used nowhere in the manuscript

Thank you

Yasir E A Elsanousi

Competing interests

The author declares that they have no competing interests.