To estimate the average strength of vaginal palpation and vaginal squeeze pressure in primigravid, the investigators used the following equation to scale the sample: Zα/2 refers to the probability (α/2) standard one-tailed normal distribution; σ2 is the variance associated with vaginal palpation and vaginal squeeze pressure; ε is the sampling error. Based on a similar study, which evaluated similar population, it was assumed: α=0.05, σ=1.34 and ε=0.32 for vaginal palpation; and it was assumed: α=0.05, σ=12.60 and ε=3.00 for vaginal squeeze pressure. Therefore, the sample size would be 67 and 68 women, respectively.