The DEMARU states (Delhi, Haryana, Madhya Pradesh, Rajasthan, Uttar Pradesh, though the question specifies Punjab, Haryana, Himachal, and Gujarat) are notorious for their alarmingly low female sex ratio, indicating a severe demographic imbalance. This issue is a complex socio-cultural problem with deep roots, and addressing it requires multi-pronged solutions.

Causes for Low Female Sex Ratio:

1. Son Preference: This is the most significant underlying cause. Deep-seated patriarchal norms and cultural values in these states place a higher value on sons, who are traditionally seen as providers, inheritors of property, and caregivers in old age. Daughters are often perceived as economic burdens due to dowry demands and the expectation that they will move to their husband's family.
2. Female Foeticide and Infanticide: The strong son preference, combined with the availability of sex-determination technologies (despite being illegal), leads to widespread female foeticide. In some cases, female infanticide also occurs, though less commonly now. This direct elimination of female fetuses or newborns is the primary driver of the skewed sex ratio.
3. Dowry System: The pervasive practice of dowry, where the bride's family is expected to give substantial gifts and money to the groom's family, makes daughters an economic liability, reinforcing the preference for sons.
4. Lack of Women's Empowerment: Low literacy rates, limited economic opportunities, and restricted decision-making power for women in these regions contribute to their subordinate status, making them more vulnerable to gender-based discrimination, including sex-selective practices.
5. Access to Technology: The misuse of medical technology for sex determination, often facilitated by unethical medical practitioners, makes it easier for families to identify and abort female fetuses.
6. Intergenerational Transmission of Values: Patriarchal values and son preference are often passed down through generations, making it difficult to change societal attitudes quickly.

Solutions for Low Female Sex Ratio:

1. Strict Enforcement of Laws: The Pre-Conception and Pre-Natal Diagnostic Techniques (PCPNDT) Act, 1994, which prohibits sex determination, must be rigorously enforced. This includes regular raids on clinics, severe penalties for offenders, and monitoring of ultrasound centers.
2. Awareness and Advocacy Campaigns: Large-scale public awareness campaigns are crucial to challenge patriarchal mindsets, highlight the value of daughters, and educate communities about the illegality and immorality of sex-selective abortions. Initiatives like 'Beti Bachao, Beti Padhao' (Save the Daughter, Educate the Daughter) aim to change societal attitudes.
3. Economic Empowerment of Women: Providing girls and women with access to education, skill development, and employment opportunities can enhance their economic independence and social status, reducing their perceived 'burden' and increasing their value within families and society.
4. Social Security and Welfare Schemes: Government schemes that provide financial incentives for families with girl children (e.g., Sukanya Samriddhi Yojana), support their education, or offer old-age security can help mitigate the economic pressures associated with raising daughters and reduce son preference.
5. Community Engagement and Role Models: Involving local leaders, religious figures, and community groups to advocate for gender equality and celebrate the birth of daughters can foster a positive environment. Showcasing successful women as role models can also inspire change.
6. Strengthening Women's Rights and Legal Reforms: Ensuring women's property rights, combating the dowry system through stricter laws and enforcement, and promoting gender-sensitive education can contribute to a more equitable society where daughters are valued equally.

Addressing the low female sex ratio is not merely a demographic challenge but a fundamental human rights issue that requires a sustained, multi-sectoral approach to transform deeply entrenched social norms and ensure gender equality.