WASHINGTON (Reuters) -U.S. wholesale inventories increased in April amid stockpiling of prescription medication in anticipation of tariffs from the Trump administration.

Stocks at wholesalers rose 0.2% instead of being unchanged, as estimated last month, the Commerce Department's Census Bureau said on Monday. Economists polled by Reuters had expected last month's estimate would be unrevised.

Inventories, a key part of gross domestic product, climbed 0.3% in March. They advanced 2.3% on a year-over-year basis in April. Wholesale stocks of prescription medication surged 1.3% in April. There were also increases in apparel, motor vehicle, groceries and professional equipment inventories.

President Donald Trump has said he would impose tariffs on imports of pharmaceutical products that have long been spared from past trade disputes due to the potential for harm to patients. Apart from drugmakers, businesses front-loaded imports in the first quarter, seeking to avoid Trump's sweeping duties on foreign goods, resulting in a large trade deficit that subtracted a record 4.90 percentage points from GDP.

The front-running faded in April, leading to a record decline in imports and the overall trade deficit. While the contraction in the deficit at face value suggests trade could significantly add to gross domestic product in the second quarter, economists say some of the boost could be offset by low inventories.

Inventory accumulation increased at a rate of $163.0 billion in the first quarter. The economy contracted at a 0.2% annualized rate in the January-March period, the first GDP decline in three years. It grew at a 2.4% pace in the fourth quarter.

Sales at wholesalers edged up 0.1% in April after jumping 0.8% in March. At April's sales pace it would take wholesalers 1.30 months to clear shelves, unchanged from March.