During the study period, 556 LBW newborns were admitted out of a total of 1414 newborns, i.e. 39.32% of newborns. Among the LBWs, 98 died during hospitalization (17.62%), 19 were referred to other health facilities and 322 (57.9%) were lost to follow-up. Thus, we collected 136 LBW newborns, 82% of whom were born in the hospital maternity ward (in-Born). The level of education was low, with only 29.41% having attained higher education, despite a high school enrolment rate (88.97%).

The average age of the mothers was 27.53 years [extremes 15 and 44 years] with a peak in frequency between 18 and 34 years, representing 72.8% of the mothers. During pregnancy, 64 (47%) of the women had presented an obstetric complication and pre-eclampsia was the most frequent with 21.32%. The mean gestational age was 32.07 days after birth. In our population, 71 newborns (52.2%) were very premature at less than 32 weeks of amenorrhea. The sex ratio was 1.1. The birth weight was between 1500 - 2499 for 66 newborns (48.53%) with a mean birth weight of 1487 g [extremes 750 - 2400 g]. The mean height at birth was 41.52 cm, between the 10^th and 25^th percentile [extremes 33 and 48 cm] and 19 babies (14%) had a height at age below the 3^rd percentile. The mean head circumference (HC) at birth was 30.47 cm at the 50^th percentile and 22 (16.17%) had a HC at age below the 3^rd percentile. Intrauterine growth retardation was present in 60% of cases. Respiratory distress and hypothermia were the main neonatal complications with 74.26% and 68.38% respectively. The average length of hospitalization was 11.84 days [extremes 2 and 66 days]. Anthropometric parameters at birth are summarized in Table 1.

In hospital all newborns were on mixed feeding and 103 (75.73%) newborns were on parenteral feeding. At discharge, 79 newborns (58%) remained on the mixed diet. Almost all the children (92%) were breastfed. However, only 33.82% of the children under six months of age were exclusively breastfed.

· At discharge: The mean post-conceptional age at discharge was 35SA. The mean weight at discharge was 1703 g and 86 newborns (63.23%) had a weight for age below the 3^rd percentile. The mean height at discharge was 43.67 cm, between the 3^rd and 10^th percentile, and 62 babies (45.6%) had a height-for-age below the 3^rd percentile. The mean head circumference at discharge was 31.25 cm between the 25^th and 50^th percentile and 36 newborns (26.47%) had an age-related HC below the 3^rd percentile.

· At 40 weeks post-conceptional: The mean weight was 2639.27 g and 49 children (36.03%) had a weight for age below the 3^rd percentile. The mean

height was 49.67 cm, between the 25^th and 50^th percentile and 26 children (19.12%) were below the 3^rd percentile for height for age. The mean head circumference was 34.7 cm between the 25^th and 50^th percentiles and 6 children (4.41%) had a HC for age below the 3^rd percentile

· At 2 months corrected age (CA): The mean weight was 4666.76 g (between the 15^th and 50^th percentile) and 27 children (or 19.85%) had a weight for age below the 3^rd percentile. The mean height was 56.7 cm (15^th percentile) and 29 children (21.32%) had a height-for-age below the 3^rd percentile. The mean head circumference was 39.07 cm (50^th percentile) and 26 children (or 19.12%) had a HC for age below the 3^rd percentile.

· At 6 months of CA: The mean weight was 7532.35 g (between the 50^th and 85^th percentile) and 11 children (8.1%) were below the 3^rd percentile for weight for age. The mean height was 71.27 cm (between the 85^th and 97^th percentile) and 7 children (5.14%) had a height at age below the 3^rd percentile. The mean head circumference was 45.94 cm (between the 85^th and 97^th percentile) and 5 children (3.67%) had a HC relative to age below the 3^rd percentile

· At 9 months of CA: The mean weight was 8119.26 g (between the 15^th and 50^th percentile) and 5 children (3.67%) were below the 3^rd percentile weight for age. The mean height was 74.3 cm (between the 50^th and 85^th percentile) and 4 children (2.94%) had a height at age below the 3^rd percentile. The mean head circumference was 46.6 cm (between the 85^th and 97^th percentile) and 3 children (or 2.2%) had a HC for age below the 3^rd percentile.

· In total: The average weight gain from corrected PCA to 9 months corrected age was 1326.33 gr. The mean stature gain from corrected PCA to 9 months corrected age was 6.5 cm. The average gain in CP between the corrected APC and 9 months of corrected age was 3.2 cm. The evolution of the curves of the different growth parameters are summarized in Figure 1 and Figure 2.

The prevalence of LBW was 39.32%. This prevalence was higher than those reported by UNICEF worldwide (15.5%), in Africa (14.3%) and particularly in West Africa 15.4% [8]. In Senegal in 2018 the prevalence was 12% [3]. In underdeveloped countries, LBW occurs mainly because of poor fetal growth, as confirmed again by Sania et al. in Tanzania [9] [10]. Loss of sight represents more than 50% of the initial population. The high number of drop-outs could be explained by the remoteness of these children’s homes, the low socio-economic level and the health context related to the Covid-19 pandemic. In our study, we found that the frequency of LBW was higher in the 18 - 34 age group, i.e. 72.8%, and the average age of mothers was 27.53 years. These results are comparable to those of Charpak N et al. [2], Kabore et al. [11] and Luhete P K et al. [13], i.e. 27.3 years, 29.7 years and 26.6 years respectively. It is classically reported that primiparity, the age of the mothers, lack of employment, and low level of education increase the birth of premature babies or LBW [14] [15] [16].

At term (40 SA post-conception), the mean weight was 2639 g, the mean height was 49.67 cm and the mean head circumference was 34.7 cm with 36% of the population underweight at the 3^rd percentile. This was slightly lower than the average weight in Bogota (2851 g) [2] and Vietnam (2920 g) [9]. At 9 months corrected age, the mean weight was 8119.26 g, the mean height was 74.3 cm and the mean head circumference was 46.6 cm. The weight growth of the LBW children remained below −2DS for 16.17% of whom only 3.67% were below −3DS. This means that in our series, most children (84%) were able to achieve satisfactory weight gain at 9 months. Other studies have shown the same tendency for weight gain in LBW in the first year. The study by Gascoin G et al. on the evaluation of the long-term consequences of children born in the context of LBW found that most children had caught up in weight by 6 months [1] [17].

The dynamics of stature catching up in our series was more important with a better progression up to almost 90% at 9 months. Only 11% of the children had a height at 9 months lower than −2DS and 4 children (3%) had a height for age lower than −3DS. Other studies have confirmed that the majority of children have caught up in height in the first 2 years and that there is very little catching up after 2 years. Studies have shown stature recovery in the first 6 months, and at 1 year of age only 13.4% of LBW infants were below −2DS [18] [19]. However, genetic factors, including parental height, should not be overlooked in the growth potential of the child in height.

The head circumference of the children remained below −2DS at 9 months in 6% and 7 children (5.14%) had a HC for age below -3DS. Failure to catch up in HC growth at one year is still considered to be a poor prognosis [18]. Brandt et al. described the more frequent occurrence of cognitive impairment when head circumference was less than −2DS between 12 and 18 months corrected age [19].