title: Does parity increase insulin resistance during pregnancy?
abstract: OBJECTIVE
  To study the effect of parity on impairment of insulin sensitivity during pregnancy and on the risk of gestational diabetes (GDM).
  
  
  METHODS
  We studied the relationship between parity and peripheral insulin sensitivity index (ISI(OGTT)) or GDM in 1880 caucasian women, who underwent a 100-g, 3-h oral glucose tolerance test (OGTT) between the 24th and 28th gestational week and in 75 women who underwent an OGTT in two consecutive pregnancies. A proxy for beta-cell function (basal plasma C peptide/fasting plasma glucose; CP/FPG) was also measured.
  
  
  RESULTS
  By univariate analysis parity was related to decreased ISI(OGTT) and to increased CP/FPG in those with parity > 3 and likewise GDM, diagnosed in 124 women (6.58%), was linearly related to parity (P = 0.0034) and strongly age dependent. The relationships between parity and ISI(OGTT), CP/FPG and GDM were no longer significant after adjustment for age, pregestational body mass index (BMI), and weight gain. GDM was significantly related to age and pregestational weight, while ISI(OGTT) and CP/FPG were inversely related to prepregnancy BMI or weight gain. In comparison with the index pregnancy, the subsequent pregnancy was characterized by an increase in actual and prepregnancy BMI, in 2 h area under curve (AUC) glucose and by a decrease in ISI(OGTT) (P = 0.0001). The longer the time interval between pregnancies and the higher the increment in pregestational BMI or in weight gain during the pregnancy, the greater were the ISI(OGTT) decrease and 2-h AUC glucose increase.
  
  
  CONCLUSIONS
  Parity is not directly linked to insulin sensitivity deterioration, to CP/FPG increase during pregnancy, or to GDM appearance, although it is linked through the mediation of progressive ageing and weight gain either before or during pregnancy, when there is a sufficiently long time interval between pregnancies.
authors.affiliation: Department of Internal Medicine, Spedali Riuniti, Via Monte Sabotino 96/A, 51100 Pistoia, Italy. gseghier@tin.it
authors.forename: G
authors.initials: G
authors.lastname: Seghieri
authors.forename: A
authors.initials: A
authors.lastname: De Bellis
authors.forename: R
authors.initials: R
authors.lastname: Anichini
authors.forename: L
authors.initials: L
authors.lastname: Alviggi
authors.forename: F
authors.initials: F
authors.lastname: Franconi
authors.forename: M C
authors.initials: MC
authors.lastname: Breschi
mesh_terms: D000328:Adult; D001786:Blood Glucose / Q000378:metabolism*; D015992:Body Mass Index; D003430:Cross-Sectional Studies; D016640:Diabetes, Gestational / Q000378:metabolism*; D005260:Female; D005951:Glucose Tolerance Test; D006801:Humans; D007333:Insulin Resistance / Q000502:physiology*; D010298:Parity; D011247:Pregnancy; D011263:Pregnancy Trimester, Third; D012189:Retrospective Studies; D012307:Risk Factors; D015430:Weight Gain
chemical_list: D001786:Blood Glucose