Delayed onset of lactogenesis (DOL) is an important cause for reduced exclusive breastfeeding rates. The dietary inflammatory index (DII) has been shown to be associated with a variety of adverse health outcomes, but the relationship with DOL is not well understood.

Understanding DII levels of women in the third trimester and exploring the impact on DOL.

A convenience sampling method was used to select women in the third trimester who underwent routine obstetric examinations in the First Affiliated Hospital of Anhui Medical University from December 2023 to June 2024 as the study subjects and were followed up until 72 hours postpartum, and the maternal self-perceived breast distension method was used to determine whether they were in the DOL population. General demographic characteristics and information related to pregnancy and childbirth were collected using a general information questionnaire, a food frequency questionnaire (FFQ) was used to collect information on dietary intake and calculates the DII, and the delivery and postpartum data questionnaire were used to collect relevant information about labor and postpartum. Exploring the relationship between DII and DOL using binary Logistic regression analysis and stratified the factors of age, preconception BMI, and presence of gestational diabetes mellitus.

A total of 228 questionnaires were distributed and 217 questionnaires were validly returned, with an effective recovery rate of 95.2%. Among them, 68 (31.3%) with DOL. The DOL and the non-DOL mothers were statistically different in terms of the number of pregnancies, the quality of sleep, gestational weight gain, and the presence of mother-infant separation after delivery (P<0.05). The pregnant women in the high DII group had a higher incidence of DOL than those in the middle and low DII groups according to the three quartiles of DII scores from smallest to largest (P<0.017). The results of binary Logistic regression analysis showed that the risk of DOL was 2.817 times higher in the high DII group than in the low DII group (95%CI=1.244-6.381, P=0.013). In the third trimester group of women aged<35 years with preconception BMI<24.0 kg/m², the risk of DOL in women with high DII levels was 3.144 times (95%CI=1.346-7.344, P<0.05) and 2.666 times (95%CI=1.072-6.630, P<0.05) higher than in women with low DII levels, respectively.

There was a correlation between DII and DOL, with higher DII increasing the risk of DOL, especially in the group of women in late pregnancy who are <35 years of age and with preconception BMI <24.0 kg/m². Maternal and child health care providers should provide individualized dietary guidance to pregnant women, increase the intake of anti-inflammatory diets to reduce the incidence of DOL and increase the rate of exclusive breastfeeding.