In this study, majority of the pregnant women claimed not to solely depend on TBH alone for antenatal care. Despite this, most of them did not receive intermittent preventive treatment (IPT). A study in Abeokuta showed that most of the parturients that failed to use IPT during pregnancy claimed that they were given IPT, but only pretended to swallow it during their antenatal visits (Babalola et al. 2015). More so, majority of these pregnant women preferred taking herbs believing that it is safer than conventional drugs. They were however unaware of the teratogenic and/or abortifacient potentials of herbs. Other studies from Nigeria (Fakaye et al. 2009) and other African countries (Astin 1998; Maroyi 2013) reported similar findings.
TBAs refused to disclose the herbs used in treatment of malaria. Information on herbs used in malaria treatment were obtained mainly from herb sellers (in which some of them were reluctant) and pregnant women who sourced their herbs from other means apart from TBAs. Idowu et al. (2008) identified this situation as a major setback in the documentation of essential herbs in the treatment of malaria as used by traditional healers in Nigeria.
All the traditional practitioners boldly claimed that herbs were effective in malaria treatment during pregnancy and are relatively safer (for both mothers and developing fetus) compared with conventional drugs. These findings corroborate that of Kazembe et al. (2012). However, it is relieving to know that a good proportion of the respondents are aware that not all antimalarial herbs could be used during pregnancy as they can induce abortion.
Knowledge of malaria symptoms was generally fair among the traditional practitioners. This observation supports the findings of Adeniran et al. (2016). However, all the traditional practitioners claimed to exclusively treat pregnancy-associated malaria (PAM) with herbs. These findings have serious implications for malaria control (Idowu et al. 2008).
About 17 different herbs were listed to be useful in treatment of malaria in pregnancy by both pregnant women and traditional practitioners. The herbs that made the top three were C. citratus, M. lucida, and E. chlorantha. These findings were similar to other findings on ethno-botanical survey of antimalarial plants used in Abeokuta (Idowu et al. 2010). These plants have also been reported to be used by pregnant women in other parts of Nigeria (Olajide and Adekemi 2020) and other African Counties (Malan and Nueba 2011).
A study from Abeokuta attributed the antiplasmodial properties of Morinda lucida to anthraquinones (Idowu et al. 2010). E. chlorantha and C. citatrus also possesses antimalarial properties attributed to alkaloids, terpenes and flavanolids (Ukpai and Amaechi 2012; Adebiyi and Abatan 2013).
Water was the preferred liquid by most respondents for the preparation of herbal medicines of choice. This finding is in line with another study from Nigeria (Fakeye et al. 2009). Water has been considered an inert liquid that will ensure adequate extraction of water-soluble constituents from plant materials (Fakaye et al. 2009).
This study further investigated the antiplasmodial effects of three (most frequently mentioned) plant extracts in a 6-day treatment of P. berghei-infected (pregnant and non-pregnant) mice.
Leaf extract of M. lucida in this study demonstrated a chemosuppression up to 77% in pregnant in a 6-day treatment. This is consistent with the findings of Ebiloma et al. (2011) and Idowu et al. (2014) who reported that the in vivo antiplasmodial activity of aqueous leaf extract of M. lucida carried out in P. berghei NK-65 parasitized mice showed a significant chemosuppression of up to 85.05% and 84.7% respectively. Studies from the phytochemical screening of the aqueous leaf extract of M. lucida revealed the presence of alkaloids and flavonoid as the predominant secondary metabolite (Ebiloma et al. 2011). Therefore, the observed antimalarial activity in the group treated with M. lucida may be attributed to its high alkaloid and flavonoid contents. Previous works also showed the antimalarial activity of alkaloids and flavonoids in plants (Balogun et al. 2009; Okokon et al. 2005).
Bark extract of E. chlorantha in this study showed a significant chemosuppression up to 74.32% in pregnant mice in a 6-day treatment. Other studies have reported similar findings in in-vivo evaluation of E. chlorantha against P. berghei-infected mice (Agbaje and Onabanjo 1991; Ogbonna et al. 2008).
The leaf extract of C. citratus recorded the least chemosuppression in this study with chemosuppression of up to 55.56% in pregnant mice in a 6-day treatment. This implies that C. citratus leaf extract possess minimal antiplasmodial activity hence might not be a good candidate for an alternative source of anti-malaria. This result confirmed earlier findings on in-vivo and in-vitro activities of C. citratus extract against Plasmodium parasites (Idowu et al. 2010; Kimbi and Fagbenro-Beyioku 1996).
All the extracts showed chemosuppression property which was significantly different when compared to the infected non-treated group. A complete clearance was observed in the positive control group treated with Fansidar, in the 6-day treatment. While the plant extracts showed ability to suppress parasitaemia, none was able to achieve complete parasite clearance in the 6-day treatment with extracts. This might be due to the fact that the plant extracts are in their crude forms with the active ingredients not having been isolated and compressed into active drugs (Adzu and Haruna 2007; Ebiloma et al. 2011; Idowu et al. 2014).
The fact that extract of E. chlorantha induced abortion (determined jointly by drastic loss of weight, fetal absorption, and presence of prominent endometrial glands in the oviduct) is an indication that this plant possessed abortifacient properties. This findings supports the claim by the herb sellers (that E. chlorantha can cause abortion), though some of them still prescribe it to pregnant women believing that taking a “small quantity” should pose no harm to the developing fetus. Unfortunately, there is no standard measurement for dosage requirements.
Similarly, extracts of C. citratus and M. lucida caused miscarriage in both infected and non-infected pregnant mice. A recent study also mentioned Morinda citrifolia (Linn.) belonging to the same family (Rubiaceae) with M. lucida as one of the herbs with abortifacient property (Singh et al. 2018).
However, occurrence of miscarriage was higher in the infected groups compared to the non-infected groups. Relationship between malaria and miscarriage is poorly understood. Studies on the relationship between malaria and miscarriage showed contradictory results (Schantz-Dunn et al. 2009; Takem and D’Alessandro 2013). However, this study showed that there could be a negative interaction between the use of herbs and malaria parasite infection during pregnancy. A study revealed that malaria parasite infection can reduce progesterone level in female mice (Adejuwon and Adejuwon 2005). Couple with this, are the constituents of the plant extracts. The major constituents common to these plants and responsible for their antiplasmodial activities are alkaloids, flavonoids, and saponins (Olanlokun and Akomolafe 2013)
These are known compounds to exhibit antifertility properties (Hiremath and Hanumantharo 1990; Wang and Ruan 1996). Alkaloid-like constituents were reported to be responsible for the suppressant effect on the uterine normal contraction and high anti-implantation activity exhibited by extract of Graptophyllum pictum (Stella et al. 2009).
The fact that progesterone level was low in mice treated with the plant extracts is an implication that these plant extracts possessed anti-progestogenic potential and this could further explain the cause of miscarriage observed in the pregnant mice. Studies have shown that some herbs could be anti-progestogenic (Ahmed et al. 2014; Al-Snafi 2015). The decline in progesterone in this study intensified with increase in dosage, hence explaining the increase in number of miscarriage as dosage progresses.
Progesterone act on the central nervous system, ovary and uterus, and are important for ovulation, fertilization, implantation of embryo, maintenance of pregnancy, mammary gland development, and lactation (Lydon et al. 1995; Graham and Clarke 1997).
Furthermore, progesterone is also important in suppressing the maternal immunologic response to fetal antigens, thereby preventing maternal rejection of the trophoblast (Kumar and Magon 2012).
Studies have shown that alkaloids containing plants could impair progestogenic activities (Ramya et al. 2011; Singh et al. 2018), thereby facilitating abortion and/or miscarriage. The results also suggested that these plants possessed embryotoxic (death of fetus in the uterus) properties (De Freitas et al. 2005).
It is however worrisome that there is dearth of information on the effect of these commonly used herbs against malaria on pregnancy in Nigeria. Few studies on plants with abortifacient properties did not mention these plants (Ramya et al. 2011; Ahmed et al. 2014; Takem and D’Alessandro 2013). In fact, a recent study on traditional and medicinal uses of Morinda lucida from Nigeria claimed that M. lucida posed no risk to pregnant women without any study or experiment to proof this (Adeleye et al. 2018).
More so, studies have shown that pregnant women and mothers with infants, the population that frequently uses these substances, also believe that they have no adverse reactions or toxic effects. Thus, they rarely seek information from health care professionals about herbal products (Clarke et al. 2007). However, the use of any substance, either natural or synthetic by pregnant women, must always take into account the risk-benefit ratio (Sanseverino et al. 2001).