Reply

Abstract

To the Editors:Jakobovits sustains that fragmentation in subgroups may have impaired analysis of the data presented in our article. The study included data from 8400 nulliparous and 7510 multiparous women. When divided for the 4 seasons, the smallest group was that of multiparous women in summer, with 991 cases to be distributed in the 24-hour period. Likely the number is sufficient to detect a rhythm of 24-hour frequency distribution. Although the possibility that no diurnal rhythm was detected because of the relatively small number of subjects cannot be excluded, we believe that the observation of a reduced rhythmicity in multiparous women is real. For example, the lack of 24-hour rhythm was observed also in multiparous women in spring when the 1396 cases included were more than those sufficient to detect a robust diurnal rhythm of delivery in nulliparous women in the summer season (n = 1251). Accordingly, we consider our conclusions accurate enough. It is also possible that our data, when analyzed in 8-hour time periods, do not show a significant diurnal variation. Indeed, it is not surprising that no significant rhythm is detected with the use of a rough analysis of the data, with no division between multiparous and nulliparous women, and with an unclear rationale for which the 24-hour period should be arbitrarily divided into 3 periods of 8 hours. Unfortunately, we have not evaluated whether the delivery of male versus female is different in the 24-hour period, and we thank Jakobovits for reporting this interesting and stimulating observation. To the Editors:Jakobovits sustains that fragmentation in subgroups may have impaired analysis of the data presented in our article. The study included data from 8400 nulliparous and 7510 multiparous women. When divided for the 4 seasons, the smallest group was that of multiparous women in summer, with 991 cases to be distributed in the 24-hour period. Likely the number is sufficient to detect a rhythm of 24-hour frequency distribution. Although the possibility that no diurnal rhythm was detected because of the relatively small number of subjects cannot be excluded, we believe that the observation of a reduced rhythmicity in multiparous women is real. For example, the lack of 24-hour rhythm was observed also in multiparous women in spring when the 1396 cases included were more than those sufficient to detect a robust diurnal rhythm of delivery in nulliparous women in the summer season (n = 1251). Accordingly, we consider our conclusions accurate enough. It is also possible that our data, when analyzed in 8-hour time periods, do not show a significant diurnal variation. Indeed, it is not surprising that no significant rhythm is detected with the use of a rough analysis of the data, with no division between multiparous and nulliparous women, and with an unclear rationale for which the 24-hour period should be arbitrarily divided into 3 periods of 8 hours. Unfortunately, we have not evaluated whether the delivery of male versus female is different in the 24-hour period, and we thank Jakobovits for reporting this interesting and stimulating observation. Jakobovits sustains that fragmentation in subgroups may have impaired analysis of the data presented in our article. The study included data from 8400 nulliparous and 7510 multiparous women. When divided for the 4 seasons, the smallest group was that of multiparous women in summer, with 991 cases to be distributed in the 24-hour period. Likely the number is sufficient to detect a rhythm of 24-hour frequency distribution. Although the possibility that no diurnal rhythm was detected because of the relatively small number of subjects cannot be excluded, we believe that the observation of a reduced rhythmicity in multiparous women is real. For example, the lack of 24-hour rhythm was observed also in multiparous women in spring when the 1396 cases included were more than those sufficient to detect a robust diurnal rhythm of delivery in nulliparous women in the summer season (n = 1251). Accordingly, we consider our conclusions accurate enough. It is also possible that our data, when analyzed in 8-hour time periods, do not show a significant diurnal variation. Indeed, it is not surprising that no significant rhythm is detected with the use of a rough analysis of the data, with no division between multiparous and nulliparous women, and with an unclear rationale for which the 24-hour period should be arbitrarily divided into 3 periods of 8 hours. Unfortunately, we have not evaluated whether the delivery of male versus female is different in the 24-hour period, and we thank Jakobovits for reporting this interesting and stimulating observation.