Pregnant women are one of the most vulnerable populations to malaria. Indeed, pregnant women are more susceptible to plasmodial infections even though these are often asymptomatic . This susceptibility is in part due to the depression of the immune system during pregnancy which allows women to tolerate the fetus . The effectiveness of IPT-SP has been demonstrated in sub-Saharan Africa [13–15] and in a few localities in Gabon [1, 3]. However, no data regarding the semi-urban and rural regions in southeastern Gabon have been published to date. The objective of this study was, on one hand, to evaluate the level of attendance to prenatal counselling services, and on the other hand, to assess the adherence rate of parturient women to IPT-SP and its impact on newborns, in rural and semi-urban areas in southeastern Gabon.
The mean age of parturient women was the same as the one found in urban regions in Gabon (the capital Libreville and its surroundings) . Moreover, the same trends were observed in several countries of sub-Saharan Africa such as Benin, Burkina-Faso and Senegal [13, 14, 16].
The PNC attendance rate (Figure 1) is significantly higher than the one observed in Libreville and its surroundings (urban area) in 2011  and in other countries in Africa such as Kenya  and Benin . These results show a significant improvement in the monitoring of pregnant women in Gabon, probably due to multiple awareness campaigns and free childbirth care since 2017 (for any woman attending a PNC in a health structure recognized by the National Health Insurance Fund in Gabon). In total, 90% of parturient women received at least one dose of IPT-SP and 58.87% received at least three doses, as recommended by the WHO for good adherence. Indeed, since 2003, Gabon has adopted WHO recommendations  for prenatal care and led extensive awareness campaigns on the necessity of using IPT-SP. Our results show a good adherence rate of pregnant women to this new malaria control measure in southeastern Gabon, as is the case in other regions of the country. Indeed, studies led in the capital Libreville and its surrounding areas, Lambaréné and Fougamou have shown that the adherence rate to IPT-SP is good, and has led to a significant decrease in malaria prevalence in pregnant women [1, 3, 4, 6, 20]. Similar results were noted in other African countries such as Kenya or Burkina Faso [21, 22] though a low adherence rate to IPT-SP was reported in an urban area in the south of Benin in 2017 . However, it should be noted that the rate of women receiving at least three doses of IPT-SP during their pregnancy has not changed much since 2007 [3, 4]. These data support the fact that in urban centers, certain categories of women do not have access to socio-economic development. In Gabon, it is therefore urgent to explore new factors which may limit an excellent coverage of IPT-SP.
Moreover, our study showed that parturient women aged less than 18 years old were those with the lowest adherence rate to IPT-SP (Table 2). This could be explained by the fact that these pregnant women were also those who attended PNC the least during their pregnancy (p < 0.001), given that prophylaxis with SP is administered to pregnant women during PNC. Indeed, a study performed in Libreville showed that the adherence to IPT-SP was statically linked to the attendance of prenatal counselling services . Our results are also consistent with those of studies in the Democratic Republic of the Congo and in Burkina Faso, which showed that teenagers were less likely to attend PNC during pregnancy  and less likely to adhere to IPT-SP. These results could be due to several factors such as financial and geographical constraints, the lack of knowledge on pregnancy risks and the lack of education on the importance of prenatal care. The low attendance to PNC could also be due to socio-cultural aspects such as the shame of being seen by relations, or beliefs according to which a pregnancy can be cursed or unsuccessful if it is revealed too early [23–25]. In contrast to parturient women aged less than 18 years, the 30 – 35 age group had the highest attendance rate to PNC and the best adherence rate to IPT-SP (. This can be explained by the fact that it is in this age group that are found wanted pregnancies, due to marital status or age, and these women carefully seek and follow prenatal care. Our study showed that the professional status of women impacted the attendance rate of PNC as well as the adherence rate to IPT-SP. Indeed, several Gabonese women declared that in the case of IPT-SP stock shortage in prenatal counselling services, pregnant women are often asked to buy their dose of IPT-SP themselves in drugstores, which is often very difficult for this underprivileged population. This was demonstrated in Burkina Faso in a study by Sinare-Ousmane in which 71% of parturient women did not take enough doses of IPT-SP because they were required to pay for treatment . These observations are consistent with results obtained by Amani-Maleya et al in 2019 in the Democratic Republic of the Congo . Furthermore, several studies have shown the importance of economic welfare and educational level for the adherence to IPT-SP [15, 16, 27].
The mean weight of newborns did not differ significantly with the one reported in Libreville between September 2005 and January 2006 (Bouyou-Akotet, et al., 2010) after the implementation of IPT-SP in Gabon. This is not surprising as pregnant women are offered the same care in urban, semi-urban and rural regions in Gabon. The good adherence rate to IPT-SP in this study supports this result. Many studies have highlighted a decrease in low birth weight with the adoption of IPT-SP [28–30]. In our study, we shown that birth weight was statistically linked with IPT-SP (Table 5). Indeed, we noted a significant birth weight gain for newborns whose mothers took three doses of IPT-SP. These data confirm those previously reported in Libreville and Lambaréné [1, 3] and in several countries of sub-Saharan Africa . Despite the high prevalence of genotypes associated with resistance to SP in some rural areas in Gabon , the three-dose IPT-SP policy must be maintained and improved in order to make it accessible to all pregnant women for effective malaria control.
The prevalence of plasmodial infection in pregnant women was lower than those reported by Bouyou et al in 2010 in Libreville and by Mario Jäckle et al in 2011 in Fougamou (in the rural province of la Ngounié in Gabon). The low prevalence observed could be a consequence of the adherence to IPT-SP and treatment recommendations, or self-medication. Besides a good global rate of IPT-SP coverage (90%) and a good adherence rate to IPT-SP (58.87%), we found no link between infection and prevention measures such as the use of LLINs, knowledge on malaria or window screens (Table 4). Furthermore, the prevalence of malaria in peripheral blood in pregnant women found in this study is lower than those reported in 1995 (25%), in 2005 (12%) and in 2011 (6%) . However, parasitic sequestration and submicroscopic infections support an overestimation of this prevalence. Indeed, a study showed that malaria diagnosis by polymerase chain reaction (PCR) leads to a better estimate of malaria prevalence after treatment with SP, since the parasite load decreases in populations after the implementation of new disease control strategies . These infections are a part of plasmodial reservoir. In this study, P. falciparum infection was associated with low birth weight and premature births (Table 5). Similar results were found in Libreville  and in several other studies [31, 35]. Indeed, the presence of parasite in placenta disrupts exchanges between the mother and the fetus, thus limiting its development. We found no link between plasmodial infection, age and obstetric history (gravidity and parity) of parturient women, unlike previous studies [20, 32, 36–38]. Indeed, it was shown that the decrease in malaria prevalence in pregnant women thanks to prevention means cancels the effect of age and obstetric history on infection [39–41]. The low prevalence of plasmodial infection observed in our study corroborates these observations
Our study has a few limitations. The data gathered on the attendance of PNC and the adherence to IPT-SP were largely based on hospital birth registries (CHRPMK). The data of several parturient women were missing and could not be included in our analyses. In addition, during data collection from January 1st to April 30, 2020, several parturient women were reluctant to answer the questions while others forgot some of their medical information. Finally, the parasitological examination of the umbilical cord and placenta could not be performed especially as P. falciparum is often sequestered there, and placental infection is considered as one indicator of malaria in pregnant women .