Determining safe limits for the length of labor has increasingly become a topic for debate. While there are a number of known associations between mother and daughter reproductive outcomes, there are no reports in the literature comparing the length of labor in daughters versus their mothers. Having this information may help providers better assess labor progress in nulliparous women. The aimof this study was to investigate the associations between length of labor in nulliparous women and in their mother's first birth, to construct individualized predictive models for labor. This was a mother-daughter matched cohort study, conducted in 2 Israeli maternity hospitals between September 2014 and June 2015. Nulliparous women were eligible for the study if they had singleton pregnancies at.32 weeks' gestation and if their biological mothers had their first birth in a hospital prior to 1997. Data on the daughters were gathered through prospective questionnaires and electronic hospital records, and data on themothers were gathered through retrospective recall questionnaires. A total of 323 mother-daughter pairs were analyzed. In the univariable logistic regression model, daughters whose mothers had labored for more than 10 hours with their first born were almost 2 times more likely to also have long labors of more than 10 hours (odds ratio [OR], 1.91; 95% confidence interval [CI], 1.19.3.05; P = 0.007). Adjusting for same-gender offspring increased these odds to greater than 3 (OR, 3.23; 95% CI, 126.96.36.199; P = 0.002). The likelihood of longer labor among daughters increased with increasing age and gestational weight gain (OR, 1.09; 95% CI, 1.04.1.14; P < 0.001; and OR 1.11; 95% CI, 1.05.1.16; P < 0.001, respectively). Shorter labor in daughters was significantly associated with the lack of epidural anesthesia during labor (OR, 0.22; 95% CI, 0.10.0.47; P < 0.001). The multivariable logistic regression model showed significant associations for the daughters' length of labor and such factors as mothers' length of labor (OR, 1.88; 95% CI, 188.8.131.52; P = 0.017), daughters' age (OR, 1.08; 95% CI, 1.02.1.14; P = 0.005), and weight gain in pregnancy (OR, 1.10; 95% CI, 1.04.1.16; P < 0.001). Women who did not use any anesthesia during labor were less likely to have a longer labor than those who had epidural anesthesia (OR, 0.27; 95% CI, 0.12.0.60; P < 0.001). The multivariable regression model seemed to predict length of labor with 66% accuracy, 74% sensitivity, and 56% specificity. The model found that 66% of daughters predicted to have long labors did indeed do so and that 64% of daughters predicted to not be at high risk of long labor had labors of more than 10 hours. In conclusion, mothers f length of labor and their daughters f age, gestational weight gain, and use of anesthesia were significantly associated with the daughters' length of labor. This information, along with evidence, signs, and symptoms, may be used to help predict labor progression in nulliparous women.