The purpose of a study by Halligan et al. (A-28) was to evaluate diurnal variation in blood pressure (BP) in women who were normotensive and those with pre-eclampsia. The subjects were similar in age, weight, and mean duration of gestation (35 weeks). The researchers collected the following BP readings. As part of their analysis they studied the relationship between mean day and night measurements and day/night differences for both diastolic and systolic BP in each group.

C1 C2 C3 C4 C5 C1 C2 C3 C4 C5 0 75 56 127 101 1 94 78 137 119 0 68 57 113 104 1 90 86 139 138 0 72 58 115 105 1 85 69 138 117 0 71 51 111 94 1 80 75 133 126 0 81 61 130 110 1 81 60 127 112 0 68 56 111 101 1 89 79 137 126 0 78 60 113 102 1 107 110 161 161 0 71 55 120 99 1 98 88 152 141 0 65 51 106 96 1 78 74 134 132 0 78 61 120 109 1 80 80 121 121 0 74 60 121 104 1 96 83 143 129 0 75 52 121 102 1 85 76 137 131 0 68 50 109 91 1 79 74 135 120 0 63 49 108 99 1 91 95 139 135 0 77 47 132 115 1 87 67 137 115 0 73 51 112 90 1 83 64 143 119 0 73 52 118 97 1 94 85 127 123 0 64 62 122 114 1 85 70 142 124 0 64 54 108 94 1 78 61 119 110 0 66 54 106 88 1 80 59 129 114 0 72 49 116 101 1 98 102 156 163 0 83 60 127 103 1 100 100 149 149 0 69 50 121 104 1 89 84 141 135 0 72 52 108 95 1 98 91 148 139 C1 ¼ group 0ð Þ ¼ normotensive; 1 ¼ pre-eclamptic ; C2 ¼ day diastolic; C3 ¼ night diastolic;
C4 ¼ day systolic; C5 ¼ night systolic.
Source: Data provided courtesy of Dr. Aidan Halligan.