The proportion of new mothers who start to breastfeed their babies has risen in the past five years from 76% to 81% across the UK, according to new official figures.

The infant feeding survey finds a significant increase in England, Wales and Scotland, although not in Northern Ireland.

There is great regional variation, however, and striking difference between women of different backgrounds. Those with professional and managerial jobs and higher levels of education are most likely to begin breastfeeding.

Across the UK, 90% of women in managerial and professional jobs began breastfeeding (up from 88% in 2005), compared with 74% of those in routine and manual occupations and 71% of those who have never worked (both up from 65% in 2005).

There is also a direct relationship between the amount of education a woman received and starting to breastfeed.

Among those who left full-time education after the age of 18, 91% initiated breastfeeding, but among those who left at 16 or earlier the figure was only 63%.

First-time mothers are also more likely to start breastfeeding than those having a subsequent child – 84% against 78% in the UK.

The report, from the Office for National Statistics (ONS), compiles figures only for women who begin breastfeeding.

There has always been a steep drop in the numbers continuing to breastfeed, but whether this has changed will not be known until the next stage of the survey is published next year.

The ONS has also produced statistics on the numbers of women smoking during pregnancy, which fell between 2005 and 2010 from 33% to 26%.

Women in routine and manual jobs were the most likely to smoke (40%, down from 48% five years ago), while those in professional and managerial jobs were the least likely (14%, down from 20%).

Those who smoked throughout the whole of their pregnancy were most likely to have never worked (21%), with the rate only 4% among professional and managerial women.

The younger women were, the more likely they were to smoke – 57% of under-20s compared with 15% of the over-35s.

Unicef, which accredits hospitals that have good breastfeeding practices, said the rises were a tribute to the work that has gone on in the NHS.

"In recent years hospitals have put great effort into improving staff training and knowledge, and putting in place policies and practices proven to increase breastfeeding rates," said Sue Ashmore, Unicef UK's baby friendly initiative director. "Now we have the figures to show this nationwide effort has paid off."

Rosie Dodds, senior policy adviser for the National Childbirth Trust, said: "It's great news that more women are starting to breastfeed and that more are getting the support they need to stop smoking while they are pregnant.

"Four-fifths of new mothers plan to breastfeed – we don't yet know how many are enabled to continue ... We do know from previous surveys that most find that they have to stop breastfeeding before they want to because they do not get the help they need.

"Every year more than 200,000 mothers stop breastfeeding in the first few days and weeks – 90% of these mothers would have liked to continue.

"In Norway, Canada and Sweden more than 90% of mothers start to breastfeed and most continue without problems."

The health department confirmed it had withdrawn funding for this year's National Breastfeeding Awareness Week and nine regional infant feeding co-ordinators.

A spokesman said: "The department recognises the importance of breastfeeding, and we continue to support breastfeeding through the healthy child programme, as set out in the public health white paper.

"We have made the challenging commitment to an extra 4,200 health visitors by 2015. Health visitors will be able to help support women who want to breastfeed but may find it difficult."

He added: "Breastfeeding is good for babies and mothers so it is encouraging to see an increase in the number of women who start breastfeeding."