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Year : 2020  |  Volume : 33  |  Issue : 3  |  Page : 1063-1066

Effect of vaginal pH in preconceptional fetal sex determination

1 Dermatology and Sexology Department, Faculty of Medicine, Menoufia University, Shebeen El-Kom, Egypt
2 Department of Obstetrics and Gynecology, Faculty of Medicine, Menoufia University, Menoufia, Egypt

Date of Submission19-Nov-2018
Date of Decision23-Dec-2018
Date of Acceptance30-Dec-2018
Date of Web Publication30-Sep-2020

Correspondence Address:
Nashwa H Allam
Dermatology and Sexology Department, Faculty of Medicine, Menoufia University, Shebeen El-Kom, Menoufia
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/mmj.mmj_338_18

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To assess the effect of vaginal pH on fetal sex determination.
Sex determination is a very important topic. Changing of the normal vaginal pH (3.8–4.5) can affect the activity of different types of spermatozoa and therefore affect the fetal sex.
Patients and methods
This prospective study was carried on 20 patients coming to clinic of gynecology and obstetrics, with variable ages ranging from 21 to 37 years and free of any gynecological or obstetric disorders; vaginal swab from each case was taken on a litmus paper on preovulatory time to assess the acidity and alkalinity of vagina and define its effect on fetal sex.
Overall, 20 patients were from different gravidity and parity. Regarding the comparison between acidic and alkaline vaginal pH and fetal sex, there were significant associations between fetal male sex and alkaline vaginal pH, and significant association between fetal female sex and acidic vaginal pH.
Vaginal pH could be used as a natural method to determine the fetal sex.

Keywords: acidity, alkalinity, fetus, sex, vagina

How to cite this article:
Gaber MA, Saleh SA, Allam NH. Effect of vaginal pH in preconceptional fetal sex determination. Menoufia Med J 2020;33:1063-6

How to cite this URL:
Gaber MA, Saleh SA, Allam NH. Effect of vaginal pH in preconceptional fetal sex determination. Menoufia Med J [serial online] 2020 [cited 2021 Mar 1];33:1063-6. Available from: http://www.mmj.eg.net/text.asp?2020/33/3/1063/296665

  Introduction Top

Sex determination is a biological process for determining the development of the primordial gonads into male (testes) or female (ovary) gonads [1].

Clinical importance of fetal sex determination

Antenatal complications and fetal sex

A pregnancy with a male fetus has been associated with an increased risk of pregnancy complications and adverse obstetrical outcomes. A study by Sheiner et al. [2] was done comparing 55 891 pregnancies with a male fetus and 53 104 with a female fetus, and it found that when the fetal sex was male, pregnancies were found to have higher rates of fetal macrosomia, failure to progress during the first and second stages of labor, cord prolapse, nuchal cord, and true umbilical cord knots. Cesarean section rates were found higher among pregnancies with male compared with female fetuses. They have found that having a male fetus was significantly associated with nonreassuring fetal heart rate patterns and low Apgar scores at 5 min. They concluded that male sex is considered an independent risk factor for adverse pregnancy outcome. Actually, some of the observations of this study can be interrelated, for example, it is well known that fetal macrosomia can lead to prolonged both first and second stages of labor, which in turn can result in an increase in the cesarean delivery rates, but the mechanism standing behind higher rates of macrosomia in male fetuses is not clear yet. Sex hormones, fetal insulin, and genetic factors can all interact to result in higher weight of male fetuses compared with female fetuses for a given gestational age [2].

Fetal sex and maternal glucose tolerance

Studies examining an association between fetal sex and abnormal maternal carbohydrate metabolism have yielded conflicting results. One study found that after adjusting for maternal parity, age, race, pre-pregnancy BMI, education, history of gestational diabetes, smoking and alcohol use, and gestational age at blood glucose measurement, a female fetus may be associated with greater maternal insulin resistance during pregnancy [3]. Decrease the consequences on the fetus.

Fetal sex and hypertension

Shiozaki et al. [4] conducted their study in 125 centers in Japan from 2001 through 2005. They found that in singleton, monochorionic diamniotic, and dichorionic diamniotic (DD) pregnancies, pregnant women carrying female fetuses had a significantly higher incidence of pregnancy-induced hypertension (PIH) and preeclampsia compared with those carrying male fetuses, whereas twin pregnancies with male–female fetuses had intermediate values. Moreover, they found that the incidences of PIH and preeclampsia in monochorionic diamniotic twin pregnancies were similar to those in DD twin pregnancies with male–male fetuses or female–female fetuses. They concluded that female fetal sex was a risk factor for both PIH and preeclampsia, whereas the male antigen and the increased number of major histocompatibility complex mismatches in DD twin pregnancies may not be a risk factor for PIH and preeclampsia.

Fetal sex and preterm delivery

There was a study which concluded that most preterm labor (PTL) cases are pregnant with a male fetus, and these pregnant women deliver slightly earlier, but race appears to affect this disparity. They performed a secondary analysis of a prospective cohort study including women with symptoms of PTL between 24 and 34 weeks. They had calculated the proportion of women carrying a male or female fetus at the onset of PTL. Gestational age at delivery and risk of preterm delivery (PTD) of both fetal sexes were compared, and the interaction of maternal ethnicity and fetal sex on the risk of PTD was evaluated. Of the 594 included women (55% were male pregnancies), median gestational age at delivery in women carrying a male fetus was 37 5/7 weeks compared with 38 1/7 weeks in women pregnant with a female fetus. The risk of PTD did not differ significantly. In whites, they did find an increased risk of PTD before 37 weeks in women pregnant with a male fetus (odds ratio 1.9; 95% confidence interval: 1.2–3.0) [5].

Fetal sex and fetal growth

In a recent study, the applications of these differences were used to customize fetal growth charts based on fetal sex. Investigators constructed customized biometric growth charts for fetal sex, parental, and obstetrical characteristics using quantile regression. In this large multicenter cross-sectional study, 8070 ultrasonographic examinations from low-risk singleton pregnancies between 16 and 40 weeks of gestation were examined. They obtained the following fetal measurements: biparietal diameter, head circumference, abdominal circumference, and femur length. Quantile regression was used to examine the effect of fetal sex across the biometric percentiles of those fetal measurements considered together with parents' height, weight, parity, and race. They found that fetal sex was a significant covariate for biparietal diameter, head circumference, and abdominal circumference, with higher values for male fetuses, and minimal differences for femur length were found among sexes [6].

Fetal sex and fetal heart rate monitoring

There was a study that examined the antepartum fetal heart rate indices, dynamics, complexity, and reactivity to the nonstress test and vibroacoustic-stimulation test of a total of 3835 (1849 females and 1986 males) singletons who were delivered at term without maternal and fetal complications. They suggested that the cardiovascular system of female fetuses matures earlier than that of males because female fetuses exhibited greater heart rate dynamics in early gestational periods but male fetuses undergo a compensatory period of rapid changes to catch up with females at term [7].

Fetal sex and birth weight

There was a study that analyzed birth outcome data from singleton infants who were enrolled in a large randomized, double-blind, placebo-controlled trial of neonatal vitamin A supplementation conducted in Tanzania. Among 19 269 singleton Tanzanian newborns included in this analysis, 68.3% were term deliveries and appropriate for gestational age, 15.8% were also term deliveries but small for gestational age (SGA) (defined as birth weight <10th percentile), 15.5% were PTDs and appropriate for gestational age, and 0.3% were preterm and SGA. In their multivariate analyses, they have found that male fetus was a significant risk factor for term-SGA (P < 0.05) [8]. A book in Japan by Rovik translated into Japanese in 1970 introducing theory and practical approaches of sex selection, there is a concept of selection based on the physiological difference of the sperm activation and motility depending on the environmental pH between X and Y spermatozoa. Although acidic environment weakens both spermatozoa, but X spermatozoa are more resistant than Y spermatozoa against acidic media, leading to dominant survival of X spermatozoa over Y spermatozoa in acidic environment of the vagina. By contrast, alkaline environment strengthen the activity of both types of spermatozoa, and Y spermatozoa are more activated than X spermatozoa; consequently, it is believed that Y spermatozoa will dominantly survive over X spermatozoa in alkaline environment [9]. Male sperms are adversely affected by acidity, and if a mild acidic substance is introduced into the vagina before intercourse, conception of a girl is more likely [10]. Because of all these views that talk about the effect of the acidity and alkalinity of vagina on different types of spermatozoa, it was very important to search about this effect to use vaginal pH as a natural cheap method for preconceptional fetal sex determination.

  Patients and Methods Top

This prospective study was conducted at outpatient clinic of Gynecology and Obstetrics Menoufia University Hospital from March 2017 to March 2018 and included 20 patients at different ages from 21 to 37 years. A written consent was taken from each case after procedure had been fully explained: all the patients were chosen in accordance with the following criteria: inclusion criteria were patients who came to the clinic of Gynecology and Obstetrics desiring pregnancy, and exclusion criteria were any systemic or local disease that may affect vaginal pH at the time of ovulation such as diabetes mellitus or vaginitis or cervicitis. The study design is a prospective one. Patients were subjected to the following: full history taking, personal history, other important medical problems as in obstetric and gynecological history, gravidity and parity, and any recent genital tract infection, and full drug history to exclude any medications, local or systemic, that may affect the vaginal pH and therefore affect our study results. Twenty vaginal swabs were checked by litmus papers from each case attending the clinic desiring pregnancy at the time of ovulation, which can be detected by different methods. These include either the rough methods, based on the first day of the last menstrual cycle, or a simple at-home test, where the mother can do it by herself in early morning at bed and before any physical activity by measuring the body temperature by thermometer, what is called basal body temperature test, where the temperature increases half a degree at the day of ovulation; luteinizing hormone follow-up, as its level increases at the time of ovulation; and vaginal ultrasound (folliculometry), which can measure the diameter of the ovarian follicle once the ovum's diameter reaches 20 mm at the time of ovulation. The cases according to their different vaginal condition were divided into acidic and alkaline groups. After pregnancy occurs and after a few months once fetal sex can be defined by ultrasound, women's vaginal pH as previously recorded can be correlated with the fetal sex of each case [Figure 1].
Figure 1: Association between vaginal pH and fetal sex.

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Statistical analysis

Data obtained from the present study were computed using SPSS versions 17 (SPSS Inc., Chicago, Illinois, USA) under the platform of Microsoft Windows XP (NASDAQ-100, Dow Jones Industrial Average, USA), Professional Edition. Continuous data were expressed in the form of mean ± SD whereas categorical data were expressed in the form of count and percent. Comparisons of continuous data were performed using Student t-test, whereas categorical data were done using χ2-test. P value less than 0.05 was considered statistically significant.

  Results Top

Regarding the relation between fetal sex and vaginal pH, there was a significant association between acidic vaginal pH and female fetuses and significant association between alkaline vaginal pH and male fetuses (P = 0.007) [Table 1].
Table 1: Relation between fetal sex and vaginal pH

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Regarding the reliability of vaginal pH in detecting fetal sex, there was good reliability of vaginal pH assessment in the prediction of fetal sex [Table 2].
Table 2: Reliability of vaginal pH in detecting fetal sex

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Relation between vaginal pH and the basic data. There was significant association between acidic vaginal pH and higher age and BMI (data not shown in tables).

Relation between vaginal pH and obstetric data. There was no significant association between women with acidic and alkaline vaginal pH and their parity and gravidity condition (data not shown in tables).

  Discussion Top

Dubuc and Sivia [11] reported that sex selection is a controversial issue. The preference of sons and prenatal sex selection against females have resulted in significant imbalances in sex ratio at birth in several Asian countries, including India and China. Scherker [12] reported that Y spermatozoa had a greater tolerance to alkaline pH than X spermatozoa and they moved faster in this media, whereas the reverse being true for acidic pH. To the best of our knowledge, this study among the recent studies that have discovered the role of vaginal pH in fetal sex prediction. It found that there was significant higher rate of male fetuses who were conceived by mothers with alkaline vaginal pH and also there was significant higher rate of female fetuses who were conceived by mothers with acidic vaginal pH.

Recently, the study by Oyeyipo et al. [13] aimed to separate X-chromosome and Y-chromosome-bearing spermatozoa using methods based on the viability difference between the X-chromosome and Y-chromosome-bearing spermatozoa. A total of 18 experimental semen samples were used, and written consents were obtained from all the donors, and the results were analyzed in a blind fashion. Spermatozoa were exposed to different pH values (5.5, 6.5, 7.5, 8.5, and 9.5), increased temperatures (37, 41, and 45°C), and ROS levels (50, 750, and 1000 μmol/l). The results indicated successful enrichment of X-chromosome bearing spermatozoa upon incubation in acidic media, increased temperatures, and elevated H2O2.

In our study, there were no statistically significant differences between women with acidic and alkaline pH regarding follicular phase length, which is in harmony with Gray et al. [14] who performed a prospective study on women who were using natural family planning. Charts were used to assess the most probable day of insemination relative to the day of ovulation and length of the follicular phase of the cycle. The fetal sex ratio did not vary consistently or significantly with the estimated length of the follicular phase or with the planned or unplanned status of the pregnancy.

  Conclusion Top

The vaginal pH can be used as a cheap natural method for each couple who wants to choose the fetal sex.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

Herpin A, Schartl M. Sex determination: switch and sup-press. Curr Biol 2011; 21:R656–R659.  Back to cited text no. 1
Sheiner E, Levy A, Katz M, Hershkovitz R, Leron E, Mazor M. Gender does matter in perinatal medicine. Fetal Diagn Ther 2004; 19:366–369.  Back to cited text no. 2
Xiao L, Zhao JP, Nuyt AM, Fraser WD, Luo ZC. Female fetus is associated with greater maternal insulin resistance in pregnancy. Diabet Med 2014; 31:1696–1701.  Back to cited text no. 3
Shiozaki A, Matsuda Y, Satoh S, Saito S. Impact of fetal sex in pregnancy-induced hypertension and preeclampsia in Japan. J Reprod Immunol 2011; 89:133–139.  Back to cited text no. 4
Wilms FF, Vis JY, Oudijk MA, Kwee A, Porath MM, Scheepers HC, et al. The impact of fetal gender and ethnicity on the risk of spontaneous preterm delivery in women with symptoms of preterm labor. J Matern Fetal Neonatal Med 2016; 29:3563–3569.  Back to cited text no. 5
Schwärzler P, Bland JM, Holden D, Campbell S, Ville Y. Sex-specific antenatal reference growth charts for uncomplicated singleton pregnancies at 15–40 weeks of gestation. Ultrasound Obstet Gynecol 2004; 23:23–29.  Back to cited text no. 6
Kim KN, Park YS, Hoh JK. Sex-related differences in the development of fetal heart rate dynamics. Early Hum Dev 2016; 93:47–55.  Back to cited text no. 7
Muhihi A, Sudfeld CR, Smith ER, Noor RA, Mshamu S, Briegleb C, et al. Risk factors for small-for-gestational-age and preterm births among 19,269 Tanzanian newborns. BMC Pregnancy Childbirth 2016; 16:110.  Back to cited text no. 8
Watanabe M, Masaki H, Mori T, Tsuchiya T, Konuma H, Hara-Kudo Y, Takatori K. Inactivation effects of UV irradiation and ozone treatment on the yeast and the mold in mineral water. J Food Protection 2010; 73:1537–42.  Back to cited text no. 9
Ullman JB, Fidell LS. Gender selection and society. In: Gender in Transition. Springer, Boston, MA; 1989. p. 179–187.  Back to cited text no. 10
Dubuc S, Sivia DS. Is sex ratio at birth an appropriate measure of prenatal sex selection? Findings of a theoretical model and its application to India. BMJ Glob Health 2018: 19:e000675.  Back to cited text no. 11
Scherker JG. Gender selection cultural. Religious perspectives. J Assist Reprod Genet 2002; 19:400–410.  Back to cited text no. 12
Oyeyipo IP, van der Linde M, du Plessis SS. Environmental exposure of sperm sex-chromosomes: a gender selection technique. Toxicol Res 2017; 33:315–323.  Back to cited text no. 13
Gray RH, Simpson JL, Bitto AC, Queenan JT, Li C, Kambic RT, et al. Sex ratio associated with timing of insemination and length of the follicular phase in planned and unplanned pregnancies during use of natural family planning. Hum Reprod 1998; 13:1397–1400.  Back to cited text no. 14


  [Figure 1]

  [Table 1], [Table 2]


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