Comparative analysis of total electron content (TEC) variations and geomagnetic field variations during the major magnetic storm on 29-31 October 2003 (Kp 4-9) was carried out for the middle-latitude ionosphere. We analyzed data of GPS receivers and magnetic observatories, located in the north-east, north-west and south-west parts of North America and in central Europe. It was found that magnetic field intensity variations for the period range of 30-60 min (corresponding to the acoustic-gravity waves, AGWs) correlate well with TEC variations of the same time scale. For moderate geomagnetic activity period on October 13-18, 1999 (Kp 1-A) a similar dependence was not noticed, according to analysis of data from GPS receivers located in south-west USA, California. However, correlation between TEC variation intensity in the period range of 30-60 min and slow magnetic field changes was observed. Thus, connection between TEC variations within the period range of the AGWs and magnetic field variations is perceptible.