Inter-pregnancy weight change impacts placental weight and is associated with the risk of adverse pregnancy outcomes in the second pregnancy.
BACKGROUND
The inter-pregnancy period is considered a teachable moment when women are receptive to weight- management guidance aimed at optimising pregnancy outcome in subsequent pregnancies. In population based studies inter-pregnancy weight change is associated with several adverse pregnancy outcomes but the impact on placental size is unknown.


METHODS
The association between inter-pregnancy weight change and the primary risk of adverse pregnancy outcomes in the second pregnancy was investigated in 12,740 women with first two consecutive deliveries at a single hospital using logistic regression.


RESULTS
Compared with women who were weight stable, weight loss (>1BMI unit) between pregnancies was associated with an increased risk of spontaneous preterm delivery, low placental weight and small for gestational age (SGA) birth, while weight gain (>3BMI units) increased the risk of pre-eclampsia, gestational hypertension, emergency caesarean section, placental oversize and large for gestational age (LGA) birth at the second pregnancy. The relationship between weight gain and pre-eclampsia risk was evident in women who were overweight at first pregnancy only (BMI ≥25 units), while that between weight loss and preterm delivery was confined to women with a healthy weight at first pregnancy (BMI <25 units). In contrast, the association between weight loss and SGA was independent of first pregnancy BMI. A higher percentage of women who were obese at first pregnancy were likely to experience a large weight gain (P < 0.01) or weight loss (P < 0.001) between consecutive pregnancies compared with the normal BMI reference group.


CONCLUSIONS
Inter-pregnancy weight change in either direction increases the risk of a number of contrasting pregnancy complications, including extremes of placental weight. The placenta may lie on the causal pathway between BMI change and the risk of LGA or SGA birth.
Lifelong Health Division, Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen AB21 9SB, UK. Jacqueline.Wallace@abdn.ac.uk.
Jacqueline M
JM
Wallace
Sohinee
S
Bhattacharya
Doris M
DM
Campbell
Graham W
GW
Horgan
D000293:Adolescent; D000328:Adult; D015992:Body Mass Index; D002585:Cesarean Section / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D046110:Hypertension, Pregnancy-Induced / Q000453:epidemiology; D015994:Incidence; D007236:Infant, Small for Gestational Age; D009765:Obesity / Q000503:physiopathology; D009929:Organ Size; D010920:Placenta / Q000033:anatomy & histology*; D011225:Pre-Eclampsia / Q000453:epidemiology; D011247:Pregnancy; D011248:Pregnancy Complications / Q000453:epidemiology*; D047928:Premature Birth / Q000453:epidemiology; D012189:Retrospective Studies; D015430:Weight Gain / Q000502:physiology; D015431:Weight Loss / Q000502:physiology; D055815:Young Adult