Table 2

Key domains for data extraction

StudyFirst author
Journal
Country and year of publication
Study design
Follow-up duration
ParticipantsNumber of participants
Participant characteristics (at baseline)

  • Baseline (prepregnancy) metabolic conditions, if present.

  • Mean age.

  • Parity.

  • Ethnicity.

  • Singleton/multiple pregnancy.

  • Gestation at enrolment/recruitment.

  • Mean BMI.

  • Delivery mode

  • Breastfeeding status.


If control group is present, control characteristics (at baseline) include

  • Mean age.

  • Parity.

  • Ethnicity.

  • Singleton/multiple pregnancy.

  • Gestation at enrolment/recruitment.

  • Mean BMI.

  • Delivery mode.

  • Breastfeeding status.

Exposure* (lactogenic hormone)Hormone measured (hPL/PRL/both)
Number of time points
Time points (pregnancy), with concentration and units of hormone at each time point
Time points (postpartum), with concentration and units of hormone at each time point
Assay methodology used
Key maternal metabolic outcomes* of interest
Glucose status in pregnancy (pre-existing diabetes mellitus of any type or gestational diabetes)
Postpartum glucose status
Continuous metabolic indices related to maternal glucose/lipid metabolism, for example, measures of

  • Fasting glucose.

  • OGTT glucose of 1 and 2 hours.

  • Insulin secretion.

  • Insulin sensitivity.

  • Insulin resistance.

  • Beta-cell function (during pregnancy or postpartum).


Gestational weight gain
Obesity
Postpartum weight change
Polycystic ovary syndrome
Lipid profile (total cholesterol, HDL and LDL cholesterol, and triglycerides)		Key maternal “outcomes” assessed (from list)*
For diabetes in pregnancy

  • Pre-existing (T1DM/T2DM) or gestational.

  • Gestation at diagnosis.

  • Method used for diagnosis (eg, OGTT).

  • Diagnostic criteria, if stated.

  • Treatment (diet/oral medications/insulin) and treatment commencement time point.


For postpartum glucose status

  • Time point.

  • Method used for diagnosis (eg, OGTT).

  • Diagnostic criteria, if stated.

  • Prevalence of persistent dysglycaemia postpartum.


Relationship of said outcomes to hPL/PRL levels (as t-test result, OR, regression coefficient, etc)

  • Unadjusted.

  • After adjustment (with list of covariates included in models).


Conclusions regarding the aforementioned
Key infant metabolic outcomes* of interest (for pregnancies affected by GDM or pre-existing diabetes)
Birth weight (absolute/centiles)
Macrosomia
Growth restriction
Placental mass		Key infant outcomes assessed (from list)
Relationship of said outcome to hPL/PRL levels (as t-test result, OR, regression coefficient, etc)

  • Unadjusted.

  • After adjustment (with list of covariates included in models).


Conclusions regarding the aforementioned

  • *Due to the likely bidirectional nature of the lactogenic hormone/maternal metabolism relationship, some studies will consider hPL/PRL as ‘exposure’ and a metabolic parameter (eg, postpartum glucose tolerance) as ‘outcome’. Others may consider a metabolic parameter (eg, maternal pregestational diabetes) as exposure with hPL/PRL levels during pregnancy, in comparison to healthy controls, as outcome. The extraction template will accommodate both.

  • BMI, body mass index; GDM, gestational diabetes mellitus; HDL, high-density lipoprotein; hPL, human placental lactogen; LDL, low-density lipoprotein; OGTT, oral glucose tolerance test; PRL, prolactin; T1DM, type 1 diabetes mellitus; T2DM, type 2 diabetes mellitus.