US commercial insurance rates posted “robust growth” in the first quarter, rising almost 7% on the corresponding period last year, a Towers Watson survey shows.

Price increases were “consistent in magnitude” with rises in the preceding two quarters, with no line of business growing below 4%.

Small growth increases were noted in professional liability rates, compared with the fourth quarter last year; slight slowdowns were seen in workers’ compensation and employment practices liability.

Price rises occurred across all account sizes for standard commercial lines, with the mid-market sector the best performer.