The results of this study showed that there was a relationship between the latent Toxoplasmosis and the secondary sex ratio such that the secondary sex ratio in Toxoplasma seronegative mothers was significantly higher than in those with seropositive toxoplasmosis. Mothers with seropositive history to Toxoplasma had more female offsprings. Also, the study showed that there is a significant association between the gender of abortions and toxoplasmosis, such that Toxoplasma-seropositive mothers had higher rates of male abortion.
Previously, the relationship between Toxoplasma gondii and secondary sex ratio has been studied. Dama et al., in 2016[13], examined the possible relationship between Toxoplasma gondii and secondary sex ratio. Their findings showed that mothers with latent toxoplasmosis tend to give birth to more boys than girls. Also, in a retrospective cohort study in 2007, Kaňková et al., [14] showed that higher anti-Toxoplasma antibody concentrations increased the probability of giving birth to a boy to 0.72. They speculate that the effect of Toxoplasma on suppression or modulation of the immune system could lead to the survival of more male fetuses. In another study, Shojaee et al., [15] indicated that T. gondii infection affects secondary sex ratio in human offspring and can be addressed as one of the main causes of abortion in women. The results of the above studies are in conflict with the present study. This suggests that further research in different populations is needed to prove this hypothesis because the secondary sex ratio may be influenced by other factors in addition to toxoplasmosis such as the age of the mother, the sex of preceding siblings, immune status and other diseases [10, 12, 16, 17].
In an animal study, the researchers found that in the late phase of toxoplasmosis, mice produce more female offsprings although in the early phase of Toxoplasma infection, mice produce more male offsprings. [18]. The results of this study, similar to our study, show that the chances of a girl born are higher in mothers with chronic toxoplasmosis. This difference may be due to higher rates of male abortions in mothers with chronic toxoplasmosis, which is also reported in the present study.
The prevalence of anti-Toxoplasma IgG antibody was 16.2% in the present study, and it was significantly associated with the exposure to cats and diet. According to a study by Shaddel et al., in Shiraz,[19] the prevalence of anti-Toxoplasma IgG was 23.2% in blood donors. The cause of this disagreement can be attributed to gender imbalance in the population of blood donors most of which are men. They found that the prevalence of chronic toxoplasmosis was higher in people with low education. However, in our study, no significant relationship was found between the seropositive and seronegative groups in terms of level of education.
Fallah et al., [20] in 576 women at Gravid Primates found that consumption of raw meat and vegetables was significantly associated with the prevalence of Toxoplasmosis. We also found a significant association between eating habits, including raw and half-cooked meat, and toxoplasma antibody levels. But in this study there was no relationship between exposure to cats and the prevalence of anti-Toxoplasma antibody, while in the present study we found a significant relationship with P < 0.001.
Also, in the study of Olariu et al., the prevalence of Toxoplasma gondii antibodies in women in Romania was 57.6% and rose with increasing age [21]. In our study, the prevalence of Toxoplasma was 16.2%. The age of the population in our study had a lower mean age than the population in the study of Olariu et al. Moreover, low rate of Toxoplasma infection prevalence among our study may be due to the random selection of younger individual in this study compared to other investigations.
This study showed that abortion rates were also higher in mothers with chronic toxoplasmosis, but no association was found between abortion and the prevalence of toxoplasmosis. By Asgari et al., In 2013[22], the prevalence of Toxoplasma in spontaneous abortion samples in Shiraz was reported 14.4%, and Toxoplasma infection was recognized as a risk factor for abortion. This difference is probably due to in the sensitivity of used methods as the molecular methods used in this study is more sensitive than the serological methods used in our study.