Thanks @Mansour Khaddr !

Exactly, her K levels are shown below.

The only one more thing I would added, is that although her axis is still within normal limits, it is probably more left than should be for some one in her age where it is expected to be more vertical, and hence more prominent R-waves in lead III. In her EKG lead III has some tiny Q-waves, and inverted T-wave, which are probably related to this "subtle" axis shift in pregnancy and not due to prior MI.

In general when U wave is that prominent, K is less than 2.5 mequ/l.

When U is prominent, and relevant, like in this case I count it and label it as QT-U interval!