Pre-pregnancy obesity can have a range of effects on both the mother and the fetus, possibly due to abnormalities in maternal-fetal metabolism. Therefore, exploring the mechanisms is essential to improve fetal prognosis.

To investigate the alterations of factors associated with obesity and glucose metabolism in the placentas of pregnant women with different BMI levels before pregnancy.

A total of 100 singleton pregnant women who delivered in Beijing Shijitan Hospital, Capital Medical University in 2019 were selected as the study subjects. The clinical data were collected based on the electronic medical record system. The subjects were divided into the low/normal body mass group (n=57) and overweight/obese group (n=43) based on their pre-pregnancy body mass. The expression of long non-coding RNA metastasis-associated Lung adenocarcinoma transcript 1 (LncRNA MALAT1), serum amyloid A3 (SAA3), and interleukin 6 (IL-6) mRNA in placental tissue were measured using reverse transcription-polymerase chain reaction.

The age of the subjects ranged from 22 to 43 years, with an average age of (32.7±4.2) years, including 61 primiparas, 21 with gestational diabetes mellitus (GDM), 14 with low body mass, 43 with normal body mass, 26 with overweight, and 17 with obese. The proportion of GDM and neonatal body mass in the overweight/obese group was higher than that in the low/normal body mass group, and the weight gain during pregnancy was lower than that in the low/normal body mass group, with statistically significant differences (P<0.05). The expression of LncRNA MALAT1 mRNA in placental tissue was higher in the overweight/obese group than the low/normal body mass group, with a statistically significant difference (P<0.05). The mRNA expression of LncRNA MALAT1, SAA3, and IL-6 mRNA in the placental tissue of obese pregnant women were higher than those of normal pre-pregnancy body mass, with statistically significant difference (P<0.05) .

Excessive pre-pregnancy BMI has a more significant impact on mother and child during pregnancy, overshadowing the effects of controlling weight gain during pregnancy. In obese pregnant women, LncRNA MALAT1 may regulate glucose and lipid homeostasis through SAA3 and IL-6, involving inflammatory changes and oxidative stress, thereby affecting fetal metabolism, which deserves more in-depth exploration.