The terms SGA and LGA refer to the lower and higher weight, height, and head circumference of the infant’s body as compared to the expected length and weight, respectively [4]. Babies born with SGA or LGA are approximately 20% of all the normal births [5]. Both types of children born either with SGA or LGA are associated with a greater risk of morbidity and mortality at the time of birth. However, they may show realignment in their growth, which totally depends on their genetic growth potential [6].

The specific growth patterns for growth realignment in infants born with SGA and LGA are still not much known. However, different studies revealed several associated factors such as the infants born with LGA have a higher potential to be obese in their later life [7]. Furthermore, it may cause prolonged delivery, excessive maternal hemorrhage, genital tract tears, and higher risk of cesarean sections in mothers [8]. Due to the risk of LGA evaluated from ultrasound, intrauterine growth inhibitors are usually given, which may increase the risk of fetal death within the uterus of the mother. Furthermore, it may cause severe intestinal infection, hypoxia during delivery, diabetes, cardiovascular disease, and hypoglycemia in neonates [9]. It is because any changes in the uterus can badly affect the health of the baby in later life [10].

There are several factors that may affect the length and height of the infant. In this way, genetics play a major role as infants are more likely to be of similar height to their parents. However, it is not always apparent and a tall adult may reveal a shorter length at birth and in the first two years of his life [11]. Other than genetics, maternal nutrient intake is also considered as an important parameter that contributes to birth weight and length of a child. However, the direct association between diet quality of mother and its effect on birth length of a child has not been clearly verified [12]. Moreover, in recent years, the analysis of dietary pattern has been conducted, which revealed that unhealthy dietary patterns may increase the chances of SGA in babies [13].

Another factor includes the evaluation of mid-arm circumference. Kanawati and McLaren were the first authors who proposed the mid-arm circumference/head circumference (MAC/HC) ratio, which can be measured by using non-expensive equipment and with simple training [14]. Evaluation of mid-arm circumference is strongly linked to the birth weight and length of a baby and is considered as a suitable indicator for the evaluation of insufficient weight and height. However, it does not conducted as a part of routine evaluation for newborns [14].

Another factor that affects the baby’s health and physical appearance is maternal rest during pregnancy. It has been suggested that due to maternal stress or less rest during pregnancy, babies are physically affected. Moreover, the development of the offspring can be affected both positively and negatively depending upon the maternal energy level [15]. Moreover, it has also been reported that less maternal energy and high stress level with low rest during pregnancy result in sub-optimal growth of a baby at birth and even during different stages of infancy [16]. Also, during pregnancy, mothers are at high risk of sleep deprivation due to several reasons such as hormonal changes, mood, body temperature, and so on. This deprivation in sleep causes high stress and depression, which ultimately increase the risk of adverse fetal growth [16].

Therefore, the aim of this study is to evaluate the frequency of normal birth length and different associated factors that affect the length and growth in newborns such as maternal BMI, mid-arm circumference, consumption of extra meals, level of hemoglobin, and adequate rest during pregnancy.

Materials and methods

This retrospective cross-sectional study was carried out at the Obstetrics and Gynaecological Department of Hamdard Hospital, Karachi, Pakistan, from March 1, 2019, to August 31, 2019. A total of 195 healthy mothers and their newborns were included in the study. Institutional Review Board of the hospital gave the ethical approval of the study. Written informed consent was taken from all of the participants prior to their inclusion in the study.

The percentage frequency of the study outcome was taken as 50% for the most liberal estimate, with 95% confidence level and 7% precision, and the minimum sample size was calculated to be 196 participants.

Healthy pregnant females with either singleton or multiple pregnancies with at least three antenatal checkups were included, whereas females giving birth at gestational age less than 34 weeks or above 41 weeks and six days or with a complicated pregnancy were excluded from the study. All the pregnancies were followed up to the delivery. All the relevant data were gathered by trained data collectors with the help of a structured questionnaire, and the weight and height/length of the mothers and children were also measured.

Data were analyzed using Statistical Package for Social Sciences Version 20.0 (IBM Corp., Armonk, NY, USA). Descriptive analysis was performed by generating means and standard deviations for continuous variables, and frequencies and percentages for categorical variables. Binary logistic regression was applied to develop a risk assessment model for the study outcome while keeping the significance level at 0.05.

Results

There were a total of 195 pregnant females selected for the study. Frequency of low birth weight infants was found to be 57 (29.2%) in these women. The mean age of the mothers was 29.29±5.22 years; 142 (72.8%) of them had BMI of 25.0 or more, 102 (52.3%) had hemoglobin between 10 to 11 mg/dL, 172 (88.2%) used to take each of vitamin C and iron during pregnancy, 136 (69.7%) consumed extra meals during pregnancy, and only 5 (2.6%) were tobacco smokers/chewers (Table 1).