Lubricants Effect on Pregnancy Compared using SMI

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Lubricants effect on pregnancy compared using SMI

The use of vaginal lubricants and ultrasound gels can have deleterious effects on sperm function


Vaginal lubricants are commonly used during sexual intercourse, for sperm collection, dyspareunia, and also to assist with the insertion of medical devices, in routine examinations such as a transvaginal ultrasound.

Many of these lubricants contain previously harmless ingredients including glycerine or propylene glycol which have since been found to alter pH and osmolality levels. This change has the potential to interfere with sperm function and the likelihood of pregnancy. 

Previous studies investigated lubricants, at 10% concentration or more, for a duration of only 1 or 24 hours, which fails to mirror the true exposure of sperm to lubricants after ejaculation in the vagina.


To analyse the sperm toxicity of 5 nonspermicidal vaginal lubricants and 2 ultrasound gels commonly used, at low concentrations by sperm survival assay.


A total of 20 normozoospermic males, according to the World Health Organisation definitions, provided semen samples for this study, after 2 to 5 days of sexual abstinence.

Each sample was collected following 2 to 5 days of sexual abstinence and then analysed using computer-assisted sperm analysis (CASA). All samples were then washed using the swim-up technique and adjusted to a concentration of 20 million sperm per millilitre on an in vitro fertilisation media culture dish.

The following 5 vaginal lubricants, and 2 ultrasound gels, was analysed;

  • Durex® (Reckitt Benckiser Healthcare, UK)
  • Control® (Tecnilatex S. A., Spain)
  • Velastisa® (ISDIN S. A., Spain)
  • K-Y Jelly® (Johnson and Johnson S. A., Spain)
  • Vaginesil™ (Combe Europa, Spain)
  • Kefus® (Kefus Cosmetics S. L., Spain)
  • Aquasonic® (Parker Laboratories, USA)

All vaginal lubricants were prewarmed to 37°C and adjusted to 1%, 5% and 10% concentration in the IVF medium, with ultrasound gels tested at 10% concentration. Postwashed semen samples was then added and incubated at 37°C and 5% CO2.

The sperm toxicity of each solution was then calculated using the Sperm Motility Index (SMI) which is the percentage of progressively motile sperm divided by the control, at specific time intervals during incubation (0.5, 1, 2, 24 hours), for each semen sample. Sperm toxicity was defined as SMI < 0.75.


Initial analysis of the 5 vaginal lubricants revealed 3 distinct groups. The highest performing lubricant was Durex® with an average SMI of 0.98. This was followed by Control®, Velastisa® and K-Y Jelly® with an average SMI of 0.88-0.83. Vaginesil™ was the lowest performing lubricant with an average SMI of 0.02.

Individual analysis of the 5 vaginal lubricants according to concentration and incubation time, confirmed that Vaginesil™ was toxic within 30 minutes of incubation at all concentration levels. K-Y Jelly® was the second lowest performing lubricant exhibiting sperm toxicity (SMI = 0.69) after 1 hour of incubation at 10% concentration. After 2 hours incubation at 10% concentration, Control® and Velastisa®, also showed sperm toxicity with an average SMI of 0.74 and 0.71 respectively. On the other hand, Durex® showed no effect with an average SMI of 1.00.

ANOVA testing of the 0.5-2hr results confirmed statistically significant relationships between vaginal lubricants, time and concentration on SMI (P≤0.001).

Next, analysis of the 2 ultrasound gels also revealed differing effects on sperm toxicity according to manufacturer. Aquasonic® was toxic at all time intervals, beginning with an average SMI of 0.70 (0.5hr) decreasing to 0.22 (24hr). Interestingly, Kefus® was only slightly toxic after 2 hours of exposure (SMI = 0.69), but not at 24 hours, for unknown reasons.

Further analysis of the 2 ultrasound gels during the first 2 hours of exposure, showed that both gels had a negative impact on SMI, which decreased as exposure time increased. 

Aquasonic® Kefus®
0.5 hour0.700.78
1.0 hour0.520.74
2.0 hour0.390.69
Sperm Motility Index (SMI) results of Aquasonic® and Kefus® at time intervals 0.5, 1 and 2 hours

ANOVA testing of the 0.5-2hr results confirmed a statistically significant relationship between ultrasound gels and time on SMI (P=0.003).

The autors noted that although both Durex® and Kefus® lubricants/gels had the least effect on SMI, large-scale in vivo trails are needed to confirm these preliminary findings.


In this study, 5 out of 7 commonly used vaginal lubricants and ultrasound gels was found to be toxic to sperm (Sperm Motility Index < 0.75), within 2 hours of first contact at a concentration of only 10%, which could prevent pregnancy among couples trying to conceive.


  1. In vitro only study, with no measurement of pregnancy outcomes.


No external funding was declared for this study.


A laboratory test.

Pain during intercourse.

In vitro
An experiment performed outside the living organism usually within a laboratory.

In vivo
A medical test or experiment that is done on a whole living organism.

Normal semen sample.

The number of dissolved particles in fluid, also referred to as the body’s electrolyte-water balance.

The probability that a result occurred by random chance.

Similar studies

Mowat A, et al. (2014). The effects of vaginal lubricants on sperm function: An in vitro analysis.

Sandhu R S, et al. (2014). In vitro effects of coital lubricants and synthetic and natural oils on sperm motility.

Vargas J, et al. (2011). Sperm toxicity of “nonspermicidal” lubricant and ultrasound gels used in reproductive medicine.


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